You both have to want it to make it work. Also, you broke up BEFORE you slept with someone else?
You also didn't tell us about his personality, or your relationship, which are critical for deciding whether this is worth fighting for. Sure you have a bond with him due to your long time with him. Women who are beaten by their husbands also have a bond with them, which is one reason why they don't leave them.
I have a long time interest in psychology, specializing in relationship dynamics for 30 years.
(Please note, we give the best advice we can based on the information given in a post. For better advice, please include the age of all romantic partners.)