<human>: Give me a shortened version of the text

My best friend is this wonderful guy, we'll call him Mike. We've been close friends for almost a decade. For the past year or so, he was seeing a girl who I became really close with. In fact, I now see her more regularly than him. 

Unfortunately, she cheated on him and they have now broken up. He and I were talking about it tonight, taking a walk, and the conversation turned in an unexpected direction. See, this is the first time in the decade of friendship that we have both been single at once. He broached the idea of "friends with benefits" and I agreed that I would be okay with that, but not right away since his ex is a good friend. We both admitted to finding the other decidedly attractive, but never bringing it up before out of respect for each others' relationships.

As the night wore on and we were talking more, things got a bit more physical than expected. I let him kiss me, something he'd never done before. We made out for a while, fooled around a little bit. We didn't have sex, but it was close to that. 

Now I'm in a bit of a pickle. While this was a "long time coming" for the two of us, his ex is such a close friend but I know she would completely fall apart if she knew we even kissed, nevermind anything more! However...since she cheated on him in the first place, should I really be feeling guilty? 

I feel like I'm being true to my own feelings, but being a terrible, horrible friend. I told him nothing more would happen for a while, which he agreed was for the best. Also agreed we wouldn't mention it to her for now, since she would not handle that very well. I'm not good at keeping secrets and I'm worried that she might hear it from someone else, which would probably be worse than if I owned up to it.
<bot>: Close friend cheated on her BF. He and I are old friends and ended up fooling around. Unsure whether to feel guilty, and not sure if I should tell her.