I'd say this is an opportunity for you to think about how you want to be treated in relations that involve sexuality. Since the socalled sexual revolution in the late 1960's the traditional rules have been cast aside by people whose cultural or religious groups don't provide them with some. But interpersonal relations don't work without guidelines.
So you didn't think about any moral guidelines when the guy started to make out, assuming perhaps that alcohol gave you both permission to fool around. But then that guideline (rule) ran into another guideline (don't mess with players, and don't disrespect your friend's romantic relationships).
Seems like you both forgave each other by blaming it on the guy, and now you have to decide what to say to him about it. (I just remembered that my daughter went thru that same sleeping/making-out number about 5-6 years ago at the college where I taught. Kissing to her gave her feelings, so she was pretty hurt when she saw the cool guy between her and the other girl turn away to give equal time to the other girl. So what you don't see might not hurt you, but what you do see will probably hurt you. Or hurt the other girl that thought she was closer to him than you were. So what would you think the rule should be? That friendship between girls is thicker than fooling around, even tho toying with a stranger in bed is pretty exciting?
My approach to rule-making, since we don't have tradition to lean on, is Think of the Outcome for each person involved. Assume that for girls (and believe it or not, for over 50% of guys too) playing around sexually is going to lead to romantic feelings pretty soon, and somebody's going to be upset. So maybe apologizing for the drunken experimentation works between friends. But what to do with the guy?
I'd suggest your text him that you regret fooling around, even tho it was fun at first. But pretty soon somebody's gonna get hurt--this time it was BOTH of you girls, because girls can't keep their feelings turned off even if everything's numb when you're drunk. So what he did put some painful feelings into your friendship, and you hope he'll think about what happened this time before he does that again--with anybody.
If you're worried about shaming him and having him get nasty behind your backs in retaliation, you could add that there are girls who would make out with more than one guy in the same slumber party too. But we all know that they get "a reputation." And in fact he'll get one of those "reputations" too, if he does this for fun. [I say this because my daughter found out the the guy who'd played her also had "a reputation as a player." Because girls do talk to protect each other, and guys talk too--even though both sides are partly just blaming the other sex and warning about "users." So "players" can make use of the lax guidelines, but the rest of you learn by trial & error what feels right and what doesn't--and then announcing it is better than just hiding your regrets so the guy will still like you.
In the larger picture, our loose moral groups put stress on the emotional experiences of young people, who gradually learn to say NO to what doesn't feel good. And thus most of the rules come back pretty much the same as they were before there was "anything goes if it's exciting."
Good question, and good response from the guy. I've studied young people who sleep together, which is quite common when you're drunk. And what we don't realize is that sleeping together is quite intimate, since your heart-rate variations can begin to synchronize while you're sleeping together, even if you're out cold. So feelings of trust actually do build up, esp if you sleep together regularly. Even between 2 girls or 2 guys. And there's a primitive kind of security based love that builds up, just like a handful of kittens in a litter. Because the first time you did that was In Your Mother's Belly, and then soon after that being held by mom or dad while you were sleeping. It's animal intimacy.
When you start doing that regularly with various guys, you get what some people are calling "poliamorous relations." they're kinda exciting. And can be considered very cool in some groups. But love is a powerful chemical reaction, and in teens thru older adults its major purpose is to bring about personal growth and transformation and to manifest the highest values we can create with each other--not just the creation of new life in a zygote, but new life in two people who're containing their love with just each other.
Researchers made a big deal out of the discovery that kids who grew up together on an Israeli kibbutz rarely ever got married. For they were in effect siblings, or "litter-mates." So an unconscious taboo on sex and romantic chemistry forced them to look outside their kibbutzniks for romance. So I'd say the permission that the 60s shucking of sexual boundaries gave has resulted in frequently watering down the transformative chemistry of romantic love--love needs to be more exclusive and dangerous than that. dangerous to our expectations that we won't have to grow up, won't have to get hurt and hurt others, and won't have to die a thousand deaths when we're totally loving and have to break each other's hearts because our lives won't work together--such as one of us will crush the other.
I like what's happening afterwards. See, you folks are figuring out what it means to you to have rubbed skin too closely without noticing how you felt at the time because of the anaesthetic effect of the alcohol. Y'know, almost all of my former students would write that their first good reason for using alcohol was to make it possible to talk with the opposite sex without feeling too uncomfortable.
But there's a real value to the nervousness (and shyness & embarrassment & hurt) we feel when we're relating to somebody who's DIFFERENT and unknown and exciting. It's the kindling of the fire of love's chemistry. And all those rules of courtship were meant to keep it limited to people who could make a good outcome out of those awkward beginnings.
Your brief text-discussions afterwards (an excellent form for such awkward revelations, because you're not looking at each other, so you don't feel SO much awkwardness (aka shyness/shame) that you can't think straight.
You're getting those feelings out that alcohol anaesthetized at the time, so you're not missing out on the valuable lessons that making life's mistakes can offer you. Y'know in Alcoholic Anonymous language, we say that a person's emotional maturing ceases when they start to use alcohol to wipe out all of their uncomfortable and more painful feelings. So catching up on those feelings afterwards (and they're usually partly shame/embarrassment) keeps you from joining the celebrated TV cast of "Arrested Development." (I've never watched it, tho my daughter thinks I'd love it cuz she does--but the words fit my point like a glove.)
Are your parents divorced? Or are you just very shy?
I had less than ONE girlfriend in high school, probably because there was no presence of romantic or sexual feeling at home at all. Off to UC Berkeley 500mi away at 16 and still just crushes and an older girl's friendship (that I fell in love with). Didn't date till sophmore year. First GF lasting over 1 month was final semester of senior year @ 20.5 yrs old. It doesn't hurt to wait for love to come after you, wait till you just can't ignore it. Alcohol's a short-cut, in moderation and not habitually.
I left my college job and my class in Psych of Relationships before I'd done much interviewing and studying of "hooking up" with casual sexual performance as auditioning for the part of campus (or workplace) hot-stuff, but missing out on relationship because of so much fear of vulnerable emotions.
I know about the waiting being hard. Maybe you need a course in "proceptivity." That's when a girl gets interested in a boy, but he doesn't know it. So she has to get him to come on to her. By signalling that she would be receptive to an invitation, hence "proactive-receptive." She laughs at his jokes, asks questions about what he says, targets him with her humor, stays longer than necessary for a simple verbal interaction, makes a point of greeting him when passing by, leans toward him when talking one-on-one. Sits next to him in class (if at school). Could even practice at an online dating site. Consider every interesting potential relationship as practice for the next one; set your sights on someone you admire that isn't taken or a big flirt. Someone a little like your father, and like you.
My first real lasting GF sat next to me in 2 German classes and a Greek Tragedy class, and talked to me of course. Then 6 weeks into the semester she brought her porky little dog and asked me if I'd walk her around campus while she went to her next class. I said "Yeah, if you'll go out with me." She must have thought "It's about time!" She was afraid of love like I was, so we got along well because neither was trying to push the other where they weren't ready to go.
Nowadays it's tough for the truly virginal souls, 'cuz they don't want to let on that they're so inexperienced. In fact, sometimes a shy girl (at my college there were 8 guys for every 1 girl) has an aura of such innocence around her that the normal guys read "please don't hurt me" and just want to be safe too, as friends. Only the predators will bust their doors down, so the innocent girls may get the wrong learning about relationships: "Nobody wants me but the wolves and scumbags." But in fact, many guys are just as inexperience or more so, because they think THEY have to make all the first moves, and they haven't read the manual. So that's where Proceptivity comes in: you're making it easy for them, getting them talking, "wanna go for a walk?" And those fabulous first evening of acquaintanceship with a 4-6 hour conversation, when Time Stops.
And it can be that magical all the way through your life, so it doesn't really matter if the first one is at 14, 20, 24 or even later, 'cuz you're going to live 50-70 more years anyway.
OK I'm gone. Good night.