Well you need to clear some air and have a honest conversation. This cannot go forward unless you guys clear things out
How about you try to be friends with him again and try to be his support system.
Show from your actions that you are sorry and have changed as a person.
I tried but still he is getting more doubt.he also wants to forget everything but he is unable to do it
I am also in similar situations. My girlfriend cheated on me and left me.. I was very much in depression...but now she came back and we had clear discussion too.. but I am not able to trust her.. she try to convince that now nothing is there but old things come in my mind which I am not able to forget..
I hope you guys are fine
Just do what ur heart says