A., that's kinda a really broad question! i can tell you what happened to me, and maybe something in my story will help you out. my husband cheated on me when we were first together, a year or two into dating. i found out, and left him for almost three months. i honestly was not trying to punish him, but i felt that with a betrayal like that, i "shouldn't" be with him. i felt that i would be setting myself up for heartache after heartache if i stayed. but of course i still loved him.
then i had a long talk with a dear friend, whose hubby cheated on her when their son was a month old, and she kicked him out and never looked back. we had a long deep discussion about men in general, and i realized - she STILL hates him. and her son is now 25 years old. all this time later and she is still angry, untrusting of men, and bitter. at fifty years old, in some ways, i realized she is one of the most miserable people i know. SO i resolved not to become that, and to give it all i had. i went back, and now i couldn't be happier. we did do some counseling, but i really feel like in my husband's case, he was far from home and lonely and unhappy, and not feeling appreciated, at the time he cheated (being gone for weeks at a time due to work). i honestly don't feel he'd do it again - but when i came back to him, i laid down the law, that if he EVER did it again, whatever the reason, kids or no kids, no matter if i had family to go to or we lived three days away from my nearest friend....it would be over, no questions asked. being gone for that three months really got to him, and call it what you will, but i believe that people treat you how you allow them to, and i think i really got through to him that i wouldn't tolerate that treatment again. we have been together almost 8 years now and are still going strong, actually i think we get stronger every day.
at the same time, i know for a fact that everyone is different, and just because one thing worked for us, doesn't mean it will for you. all i can do is share my experience. i can say one more thing though, and that is, regardless of whether you have a family with this man or not, there are lots of qualities i'm sure you fell in love with in the beginning. if he's willing to WORK and so are you, i honestly don't think that divorce is ever necessary. i consider myself having gone through one of the worst tests of a relationship there is, and we made it. but both people have to be there, 100%. if either one isn't willing to work on their OWN issues, it'll never change. GOOD LUCK and i hope you find what your heart desires.