I recently found out that my girlfriend of a year has cheated on me a few months ago and then lied to my face about it. Even though all she actually did was make out, she did it with four guys on the same night. The next day she had this hickey on her neck, and told me that it was I who did it. I didn't remember doing it, but I figured it is very possible for me to forget something like that, and it didn't even cross my mind that she would lie to me. Now I just feel like an idiot. She kept this secret for a long time, in spite of me being supportive and trying to make her feel better whenever she came over my place feeling down (which, btw, was becoming exhaustingly frequent). Then, she only decided to tell me after we were laying in bed and I mentioned I'd be fine with it if she slept with other guys (Just a personal thing, it doesn't bother me if I feel secure enough, which at that point I did.) She then probably thought this was perfect because hey, I wouldn't be mad about that one time she made out with four guys and she could now finally get it off her chest! Turns she did it out of spite, because she was mad that 'I didn't want to hang out' (had homework), so she coped by going out and making out with some guys. I'd like to clarify here that for me it's not the actual cheating that hurt (as I've stated before), but the abuse of trust, the lying, and me being humiliated. My perception of her as a person was also definitely been knocked down a few pegs. If she was honest right away it probably wouldn't have been a big deal, but now I feel like all her words lost credibility. Yet in spite of all of this, I really don't want to leave her. I don't know if I'm just afraid of being alone, or she actually is worth forgiving. Everything besides this incident has been pretty good, and I don't doubt that she likes me and wants to stay with me. I've hung out with her every weekend to keep myself burning out from school, and I honestly think I'd be worse off without her. Thanks to anyone who reads this wall of text. And double thanks to anyone who offers advice.