<human>: Condense the text into a few key points

I'm 25, bi, and been out for 9 years. I'm very comfortable with my sexuality. I've also gone through a "fitness transformation" lately and look a lot more muscular than a lot of people have ever known me to be.

So recently, one of my friends (23M) who I've known for a long time asked me for training advice, so we had been talking a lot and finally he asked to come over one night. We end up having sex after hanging out for a while, and he went home.

He has a girlfriend of ~6 months who I just found out about, and I'm pretty torn up. I like him. I liked just talking. I liked having sex. I liked feeling comfortable with someone I trusted - which doesn't happen very often.

I just feel used. He will still text me when he's horny and thinking about having sex with me again, but I know he won't let it happen because of his girlfriend and how scared he is anyone will find out he's having sex with a man.

I just don't know what to do because I was excited about getting intimate with a friend I considered close. I'm in no way excited about going back to the dating pool where there's a sea of people I don't know or trust.

Any ideas or suggestions would be appreciated.
<bot>: Hooked up with "straight" friend and feeling used. Advice on how to either move on or fix things between us please.