It totally depends on how much you hurt each other. I would talk to him and feel him out. If you hurt each other very badly sometimes all thats left is resentment and anger, in that case only time will heal. I have been cheated on and I could never forgive and forget, I just couldn't trust him ever again. On the other hand sometimes it is just physical and can be seen as a mistake. Feel it out and see what is left between you two, if it is meant to be then it will be.