How do i deal with my ex fiance cheating on me for a year and a half?

My ex fiance cheated on me with this girl for about a year and a half…weve been together two years..he says he didnt have sex with her and i dont think i should believe that i have gave him chances in the past when i thought it was happening but i just ignored it.. i have gained weight but not too much i found pictures of girls i knew from our high school half naked that he printed of them and the girl he cheated on me with was skinny to i just feel so deppressed and confused i gave him my life and it