How can I stop him for being so resentful?

Hi, listen sweetie, he is feeling guilty and like a total **** right now. There is no way he as a cheater can bring himself to see you as guilty as he is. Your love is what scared him so he ran away, he simply was not ready for you don't blame yourself and don't really blame him for cheating, its just his way to escape his fear and self loathe. Give it a little time see what happens.