I think thats huge that he is offering. I would forget the past and go forward to build a new relationship, but dont take anything for granted on either side. Really treat it like you would a new relationship. Build up trust if you are both willing and able. Neither of you can change the past. Just assume you both would have done better if you could. So for now, see if you both are that better person. If he is not, then you have your answer. If he is, then you have a great relationship.