Is there any way it's going to work?

If you have no intention of getting back together with him it really doesn't matter. He's in college with is a notorious time for partying and if you two were serious before this girl is probably a rebound fling. SInce he cheated on you too just let it go. It's natural to be jealous but things will change, it took me four years and a rebound relationship to completely get over my ex-fiance. Now I couldn't care less what happens to that person.