If I have hurt a man and he now says he forgives me, but he is just a friend, should I stay away from him and give him space?

First of all, you have to understand, can the harm you have done to him be forgiven? Do you still love him? Does he still love you?

Secondly, you need to know why he doesn’t want to mention your past affairs anymore? What does he mean by saying he forgives you? Is it because time has passed and the hurt has faded and been forgotten, or is it because the hurt is too deep, but he loves you deeply and doesn’t want you to feel guilty all the time, so he tells you that he forgives you so that you don’t think too much.

Then you have to understand that since you are in the past and he is not willing or even hates you mentioning these things, then you have to learn to let go and don't go out of your way to harass or deliberately harass him. Stay away from him and just treat him as a simple acquaintance. Maybe this is what he wants.

Finally, I hope you can each find happiness, forget the past, and pursue the future O(∩_∩)O~