@Lilbeau89,
4 years is a long time, you only mention he accused you of cheating once, towards the end and in that, you moved on, with guy B, straight away? So was A right, that you were going to, even if you didn't that, you didn't feel enough in that relationship towards the end? Ask yourself.
Seems now though that as people are "talking" and as you found out he supposidly was going to buy a ring a house, you're purely thinking of what "could have been".
If you are always fighting with (B) is it because you can't love him, did you really love (A)? In-other-words is it more that you don't like being alone....
Personally, my thoughts are move out, don't be with either. Spend 6 months or so being alone, on your own and find out who you are, what you want and then decide if it really was neither, or you really did love (A)...