Judging by the replies here, it sounds like something exactly the same happened to me on Friday night.
Me and my best/only mate had been planning to go and watch a band play at a club down the road for a few weeks. It came to Friday and he and his sister (who I fancy) turned up. I decided I wanted to have a few drinks before we went so I could loosen up & dance or whatever when I got there. We had a bottle of wine each and went to the club. The night went really well, band was amazing, had a dance with my mates sister for a bit afterwards, my mate was just standing there looking pissed off and watching. I saw a few people looking over at me and began to feel a bit self-conscious but didn;t worry about it. I had about 4 pints while I was there.
When the club closed and we got back to mine, had another bottle of wine, and the subject of me staying in my flat for about 2 months a while back came up. I told my mate I wasn't going to talk about it, coz he was the only person I had told and I didn't want to go into it in front of his sister. He kept going on and on about it (hes a prick when he's drunk) and I ended up saying I had agoraphobia & was going through a really rough patch back then, he told me it was bullshit even though I'd spoke to him loads about it before, I was screwing at him about making me talk about it in front of his sister, she was telling me to ignore him because he was drunk, I ended up slamming the door on him and haven't spoke to him since.
I'm not sure how harsh I was or what exactly I'd said to him that night because I can't really remember, but I sent him a text saying 'whats happening man, sorry if I was a c**t the other night, I can't really remember what happened. Give me a bell when you can.' I've heard nothing since, so the past few days have been really bad for me, I no longer have a single friend left, and I feel really ashamed about dancing in the club (something I make sure I never do) and talking about this stuff in front of my mate's sister