It's a hard one. I cheated once when I was young and stupid and it was the biggest mistake in my life. I never felt as bad as I felt back then because I nearly lost someone I love. My bf forgave me but he never forgot it. It was bothering him our entire relationship, I changed my friends and job and wasn't going out so he wouldn't be worried about anything.. it got better with years, but one day I found out that he cheated on me with some girl from work, they had dates and kisses no sex but still.. when I asked him why he did it he said it was a pay back. What I want to tell you is that some people truly make mistakes and I would never hurt my bf again that way, but if you make a decision to forgive him then FORGIVE AND FORGET don't remind him and yourself, if you feel like it was a mistake and he loves you, forget it and leave it in the past, never talk about it - otherwise you will ruin your relationship.
Good luck

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