It sounds like your at a turning point here where you need to decide which direction you go in. The fact is you have cheated once, and have decided to do it again. Which I will not lecture you about, but will tell you is unfair to your boyfriend. Just because he is not in agreement with you about how to proceed does not give you the Ok to go out and cheat on him.
With that being said you have some choices you need to make. It is unfair for you to continue to cheat, if you have plans on meeting this new guy then you need to deal with your boyfriend. Its not ok to continue. If you want to go out again then you need to ask for a split with your current boyfriend. I know you want to work it out............but that simply is not going to work if you plan on meeting this other guy.
If you really do love your boyfriend why are you cheating?
This is a big question, you say you want to move in with each other but my question is do you really think you are ready for that kind of commitment when you are not keeping with this current commitment? If you really love your boyfriend and want to make it work, then you have to take the high road and be honest with him.
Being in a relationship takes a lot of hard work, it isn't something that simply flows without any problems. When you make the choice to be in a relationship you have to be truthful to that relationship. Pushing forward isn't what will make what you have stronger.
If you want a relationship that will stay strong and end in marriage and children then its going to take real work and real commitment. Right now your not ready to move in together, I know that isn't what you want to hear but instead of working it out you make a choice to jump ship with another man. Regardless of what you wanted for the future that does not entitle you to cheat. How would you feel if the situation was reversed...........
What if some girl came along and had sex with your boyfriend and he rationalized it with it being ok since she does not want to move in with each other and that is what he was lacking in your relationship..........would that be ok?
Of course not, so you have to ask how would you want him to handle the situation if it was him doing the cheating? Treat others as you want to be treated......if you would want him to be faithful, then you should give him that as well.
As for this other guy, it sounds like you are allowing what you want in the future to dictate what you are doing. So he is stable, but that stability does not make him a good man. You say he is a mutual friend...........what kind of friend cheats with his friends girlfriend? And then.........what kind of man does that make him?
When your looking at a relationship you need a man who you can trust. Do you think you can trust him in the future? He did cheat with his friends girlfriend...........so what is to say he will not cheat on you?
These are all good questions you need to ask yourself. I understand how frustrating it is to be in a relationship where each person has different views of where they want to be at in that relationship. But that is what being in a relationship is all about. And trust me there are going to be bigger problems in the future no matter who you end up with........you can not solve those problems by cheating now or in the future. But you can stand up and do the right thing now.
I am not saying wither you should stay with your current boyfriend or not.......only you can decide how you want to proceed, but I am telling you that by cheating you are not only hurting him but yourself as well. Trust is a hard thing to earn, and by breaking his trust your relationship will never work if you do not deal with it now. You can rationalize that he will never find out til the cows come home, but these things have a way of spinning out of control and eventually he will find out. Its better to deal with this now then wait until he finds out.
If you want to continue with the new guy and see where it leads that is fine, but first be honest with your boyfriend and break things off. Let him know that right now you feel your relationship is not moving forward and you would like to split up and see other people. This gives you the out you need to see the new guy, and preserves your dignity and your boyfriends feelings.