Hi, I’m Dr. Jackie, an interpersonal communication researcher/professor and relationship expert. I am sorry you are going through this after almost 5 years! Now to make sure I understand, you are saying he had already made plans with another person/people, assuming you two would be "on a break" for a week--and it is this week in which he already has plans? Can you clarify that for me? Because if this is indeed the case, then it sounds like he was indeed looking for an excuse to "do something with someone."
Another concern I have is that you stated he is "mad all the time, no conversation unless it's about him." This is not really a relationship, at least in terms of how experts define relationships. We equate relationships with the nature of conservation, because conversation truly does "make" the relationship. If you do not communicate, you just do not really have a relationship. You might have something else, but not a true relationship where both parties are trying to work together toward common goals (ie., parenting, spending time doing things together, etc.).
So if your "relationship" has dwindled down to this, do you think maybe you do need to take a break or whatever you want to call it to see if you really want to stay together. Based on what you have just shared, it does not seem like a relationship is a good idea right now. When couples have been together for this length of time, it's not unusual to "outgrow" it or feel like the two of you are in a different place right now. Especially if you got together when both of you were really young and really just finding your own identity, this might be a good time to really figure out if you want to continue staying together. If your answer is, "Yes," then the next step is to make a list on paper or mentally (although on paper is really good because you can visualize this) of why you want to remain in this relationship and list each advantage or blessing you get out of the relationship. Then you will need to do the opposite--list what you have to "give up" or sacrifice or "do" for the relationship. For example, maybe you would not necessarily cook much for yourself but rather eat salads or whatever. But because you are together, you cook a lot more. Or maybe you miss "Girls Night Out" but gave that up to spend time with him. Or maybe you "gave up" a religion or even TV show or whatever to accommodate him. List all of these things along with all of the advantages. Again, actually doing it on paper will help you see which list (pros or cons) is bigger. Certainly if the cons are bigger than the pros, you will want to think very hard if you don't deserve better and need to move on.
I hope that helps. Please let me know.