<human>: A friend of mine, who has been a friend since starting law school, and I had a bit of a disagreement tonight, and I was wondering whether I was being out of line or not. 

A few months ago, he asked me if I wanted to go on a "party bus" with him and some friends for our law school ball. I had initially said yes, but then told him I wasn't entirely sure, and if he wanted to replace me, go ahead and do it, but if I did make it, I'd pay him to go. He never replaced me and said it was $25 for me for $50 if I brought a date. I didn't take a date. The day of the event, I didn't go with him because I ended up across town with other friends. 

Since then, he's been whining about how I owed him $50 for not coming and has held that over my head for months. Tonight, we all went to a wedding together in a group and he brought it up at dinner. I ended up being cornered and eventiually just gave him $50 to shut him up, but I'm pretty pissed right now. He basically ruined the wedding for all of us, as it was a good friend of mine's wedding, by starting it off like that. 

I feel like it's best if I just cut ties with him if he's going to act that way. Am I wrong being a bit pissed about him cornering me during this event? I had told him I was fine paying him $25 if he was upset I didn't come, but he wouldn't let it go until I paid $50. I know I'll never agree or even suggest I'd go anywhere with him ever again.

Can you condense the text into a few key points?
<bot>: feel like I was robbed of $50, was it wrong to indulge someone's whining? Or did I do the right thing?