Best laid plans of nice and men

I'm somewhat rather shy writing this post. But the point was honesty, and I therefore must be open.  I had sex with my colleague. At conference.  We were up late drinking and flirting, and he invited me back to his room.  It was good, and orgasmic, but not the best I've ever had. But then it's the best I've had in a long while. Mild flirtation has been slowly building between us for a couple of weeks, but I really didn't think anything would happen. I didn't even go to him last night, he came to find me and stayed around for hours. I sure as hell don't want a relationship, and perhaps I may have been a little blunt on this, but we have a mutual rule of not getting involved with colleagues. That went out the window. But I'm still rather into someone else at work, much as I try not to be, and I don't want him to find out. Not to mention how awful the office gossip would be.  The pillow talk was weird though. He started telling me about his family and personal life. I didn't really want to know, I was just enjoying it for the physicality. N seemed to either actually like me, or be trying to protect my feelings, but I was enjoying embracing the sexual tension and kissing him felt so good. (Although the pash rash has not been fun trying to cover today).And it's been a while since I met a guy whose top priority is female pleasure. I was a bit selfish I think, but I'm not concerned. I knew it wouldn't be repeated so I wasn't fussed about making him want more. When saw him today i realised I'm not really attracted to him, but he looked utterly hot dressed as a miner in blue coveralls for the fancy dress costume. Not my usual type but he pulled it off.  We were both adamant that no one else can know. I'll know when I walk into the office whether he's told anyone. I'll kill him if he has.  It was good, fun and enjoyable. But finding out from another colleague today that he is engaged has shredded the pleasure and made me angry. What the fuck was he doing?! Why did he risk all that for it?why do men do this? I would not have let last night happen had I known he had a partner.  Now I know, I feel like avoiding him and / or giving him a piece of my mind. But we said we'd be workmates. I'm just not truly sure whether we can go back to that.  I just want to put it behind me, but now I've learnt about his fiancé I'm not sure I can. I hate feeling like the guilty one in all this. And I'm pretty sure he was avoiding me as much as I was avoiding him today. Oh hell. This is why you should maintain your no colleagues rule Phoenix. But I really did enjoy my night of debauchery. It's just the morning after the night before.  It's not the sex that fucks you up, it's the fallout.