I won tonight, but it was a close game.

I screwed up more than once, but it wasn't noticed. He also screwed up a couple times, but I missed it. In the end, I found a tactical line that he couldn't quite find his way through - the best continuation would just get some pieces off the board so the position was less volatile - and he ended up getting creamed. But here's a position where I screwed up majorly. I just played Nb1??, thinking it would save my a-pawn. I should not have castled queenside in the first place, it was a bad idea.

Black to move and win.

Whoops! Fortunately, he did not notice and played O-O-O instead.