Change how? Why does he want you to change?
Many people often pine for the wrong people, making us realize the better choice we had right in front of us. It’s a hard mistake, and sometimes it does cost us, but it is a mistake. However, if the person who was there all along really loves you, they shouldn’t care. If the love’s there, there should be forgiveness (in my opinion), and the feelings of that person should not be conditional.
What bothers me is that of all things to ask you to do—change for him? I’m sure we’ve all heard it, but it’s true: Never change for anybody. You should be perfect just the way you are.
So, I think you should let him go. The fact that he wants you to change in whatever way for him to just “consider” it, just isn’t right. You deserve so much better.