I slept with my best friend’s ex-boyfriend, several times.

The first time he and I were together it was because of a threesome with me, her, and him (they were still dating). I was really drunk that night and didn’t know any better; I was kind of mad at her for letting it happen.

Later on, they broke up, and he and I began hooking up. I thought I really liked him and he liked me and we had a future, but I just found out that he was just using me to add another notch on his belt.

Oh, and they took time off for a while from sex after they broke up, but apparently they’re sleeping together again.

I’m just confused and last night I was overwhelmed with guilt. Should I tell her what happened? I just don’t want a big dramatic scene, and I’ll understand if I lose her over this, but I don’t want her to tell everyone and lose other friends as well.

Please help me, my friend is graduating in four days and I don’t want this to stain our last week together.