If you are truly interested in winning him back, then do all the things you can think of that would interest him. A few important ideas:
1 no nagging- absolutely none
2 be joyful in spite of your circumstances- it's contagious and you would probably agree a happy person is much more attractive to be around than a grumpy one
3 Don't forget your exterior beauty. Often times we let ourselves go after marriage and we forget how much our husbands enjoyed looking at us.
4 One thing that helped me (my husband didn't cheat, but we had our share of problems), was to read and reread the book of "Esther" (I read it many times) in the bible and took careful notes about what it was about the queen that practically brought a very wealthy and influential king to his knees. Also take notes about what turned him away from his first wife and avoid doing those things.