I made a mistake. Should I tell him? Options

[starsandmoons]

So I've been friends with Guy X for about 4 years now and 2 1/2 of those years I was deeply infatuated or in love with him whatever you want to call it. He asked me out at one point but he was just out of a relationship and I didn't want to be the rebound. It just wasn't the right time. After a week I ended up saying yes and by that time he had decided he only saw me as a friend. For 4 years we were best friends. The closest we could get. It was amazing the type of relationship we had I could tell him anything and everything and he would do the same with me. He moved away and our relationship suffered. We were still close but not the same.

Then I met Guy Z. He was everything I could hope for in a guy. Sweetest guy, but he was deeply scarred from his past relationship where his girlfriend cheated with her ex-boyfriend of a year or so and he caught them and later she turned lesbian. Nonetheless he was very carefully with me. He wasn't as attached or attentive, which kind of made it hard on me. Sounding much like a soap opera. It gets worse. Guy Z and I were together for about 7 months when one of my best friends invites me over to a sleepover. Guy Z has just recently started talking to his ex again and I'm jealous nonetheless because he starts lying to me about it.

The sleepover. Guy X is there and he is very persistent in his flirting. I constantly push him away, but eventually I let him. We made out. A lot. I... never imagined myself doing that. Things kind of got out of hand and the sad thing is Guy Z was on my mind the entire time. My boyfriend... I love him. Guy X and I had never had even kissed or anything before this even when we "liked" each other and now at the worst moment when I had finally gotten over him and was happily taken, he does this. I did this. I cheated. I don't want to lose my boyfriend, but I feel like I need to tell him, then again telling him could mean the end of 8 wonderful months. Guy X means nothing to me. We're not talking anymore. I've completely detached myself from him. He told one of my friends who then questioned me about it trying to pressure her to tell my boyfriend. A mess.

What should I do?

[oXMuhNirvanaXo]

Yeah, I would have to say tell your boyfriend everything you did wrong and hope that he understands. I cheated before and it is the worst thing I ever have done in my life. The thing is I heard it many times before and I just thought I would never do It just because I knew I love the guy that I am with and I would never have to worry about it. Well, that changed one night. I got really depressed and I coulden't look at him the same. It was like I was liveing a lie. I tell my boy friend everything. So, 2 or 3 nights after I have done wrong he called me he was in a good mood that night and I told him everything. I told him everything I did and I told him how I felt. It tolk him a week to come and talk to me and we got back together. He cryed ALOT and he spent alot of time thinking but he said he loves me so much that he didn't wanna leave me go. So, now we are happily back together.

My friend that I have known for years I was talking to he asked me one question that hit me the deepest and that was.. "If you loved him so much.. then why did you do it."

If you care about him.. you would tell him. He has a right to know.