I've been dating my boyfriend for a year. I'm 20 and he's 22 — and I know we're pretty young, but I feel like he's the one I can't live without. The problem? He cheated on me in December. On December 25 to be exact. They were drunk and it was just a kiss, but I was so hurt. I thought it was the end. He confessed the next day, told me she meant nothing to him, and said that he would never have any kind of relationship with her. I believed him and was trying to forget everything because I really love him, but for some reason, he recently asked me to check his Facebook. When I read some of his old messages — guilty, I know — I found out that he kissed one of his friends one night and they've hung out since then. The girl was inviting my boyfriend for a drink and even asking him to stay at her place, and my boyfriend agreed to a drink.
Now I don't know what to do. Maybe a kiss is not a big deal, but every time he's with me I think he's cheated and every time he's hanging out without me I think that he may cheat again. I'm not likely to forget or forgive what he did — even though I'm really sure that he loves me and our relationship is great. Do I need to tell him that I know who he kissed and that they still hang out? Or should I just try to forget that one accident?