Tweet3 years and an engagement is real shit. The question is did you cheat before you broke it off or did you clean break off and go around. I cheated then broke up with my girl and felt guilty after every time i had sex with someone else for a while. When i went to get back she ignored me. Also one time with someone else i broke up before fooling around, didn't feel guilty, and she didnt ignore me and we dated a second time. She trusted the fact i broke up before i cheated.
I think the fact that you feel guilty says you are a good person with morals. It sucks but its not so much of a bad thing. If you love your xgirl as much as it sounds youd find a way to get her attention no matter what it took. If not you just feel guilty cause you fucked her over but you'll find someone.