So I had sex with a guy behind my GF's back. She knows I am Bi, and told me that she would have to be there in order for it to be OK and to approve of the guy as well.. She cheated on me awhile back with one of her ex boyfriends. She told me as the guilt got to her and I broke up with her over it. During that time I kind of knew what was going on and fooled around with a guy (no sex though) I told her about this as well.

She also considers masturbation cheating..

Me and her are back togeather, I'm not mad at her and she is not mad at me. I masturbate all the time behind her back because well.. I'm a guy, it's what we do, and she can't always please me (she's not in the mood, time, etc... ) But the other day I really wanted to do something with a guys... So I did.. I don't really feel that bad about it because, well a guy can please me in other ways that she can't. However I feel bad because it was sneaky... I know that if she went and slept with a girl behind my back I would not care because it's a girl..

I love her a lot and she is the ONLY women I have done anything with during our time togeather. Idk, I just don't really see masturbation and guys as cheating..

Any advice? I'm reluctant to tell her, but at the same time it's kind of one of those things I want to tell her and just get it over with, but it seems kind of selfish because
- Yes people will say, atta boy you did the right thing (making me feel better)
- I won't live with the grief anymore, and can be happy and OK

But is it REALLY worth it? Breaking her heart again? I told myself I would never do this again, and am trying to just let it go and forget about it. But I don't know what to do any thoughts?

The conscience of the human brain functions in many different ways. For some, it has no input on the things we do that one would consider wrong, others it tears them apart, makes it hard for them to sleep, eat and express yourself. The decision to tell her is ultimately up to you, and is based on the morals you carry and the morals you want your relationship based upon. I think you owe it to her to be honest seeing as she was honest with you.

I also think anyone that finds masturbation to be cheating must be a very controlling and insecure person. It's downright selfish, I encourage my girlfriend to masturbate and vice versa. Maybe you should think about moving on to someone else? I think you've already proven to yourself that you're not willing to be faithful to this girl. That should be the first sign that you are not happy with your relationship as a whole.