Mate, we've all done stupid things or stuff we regret when we're drunk.
Ultimately, I think the problem here is that girls can get funny when they find out that their guy-mates are interested in them (if they don't like them back). I'm not sure of the logic, exactly... but I think it's on the lines that the whole "friendship" was based on a lie. It's different from a guy's point of view, who would probably still take the compliment, even if he wasn't interested. If you just said you liked her, and didn't try touching her in any way, then you haven't done anything wrong... you tried your luck, and it didn't work out. That's life, sometimes you're the pigeon, other times you're the statue.
I don't think there's anything you can do... just keep your distance until it all blows over (it's only freshers week, so it will... eventually). In the meantime, on the times when you inevitably have to see them, keep it minimal and be civil. You'll know when it's OK to chat to her again. In the meantime, it won't do you any harm if you abstain from alcohol, if you are genuinely concerned about your behaviour... or at least, know your limits.