Most Helpful Guy
You don't have to prove anything. It's a difficult situation, but he's being the unreasonable one. I think the best thing to do is to leave him alone for a while. If he does go off with another lady, even just once, then he has done something that can never be put right. In that case, forget him and go find a more reasonable guy.
Most Helpful Girl
Sorry to say, you shouldn't have to deal with this, I think he did you a favour by needing time, can't you see you don't need him? Why would you want to be with someone who would doubt you after 3 years of being faithful and honest (at least I hope you were), and ESPECIALLY someone who would "knock you out"? I think you know the answer and it's to not bother any longer, you're putting yourself through hell over someone who thinks so little of you and who would get back at you as revenge for something he made up in his mind..