Made a stupid mistake :( what i do anything to make it better?

last weekend i was at a friends house party and i ended up sleeping with someone my close friend liked. at the beginning of the night they where kissing and getting close but then she started making out with other people. a few hours later i was alone with this boy and we ended up having sex. i know i messed up because i knew she liked him, but i was very drunk. i've apologised, of course, but she wont talk to me at all, yet she's talking to him. what can i do?!