Ocd over an upsetting event

Hi!
I've been having really bad thoughts about myself in the past week. Before that' I've never experienced something like that!

There was an event, to which I went alone woth my friend. I sdidn't want ti plan it with the others, because I went there by my car and didn't want to rely on anyone. But then people asked me if I can drive them tk the city. Actually they just assumed i can, since their ride already left. I couldn't say no. After an hour I said to the people, which are from my uni, but I don't know them that I am going. I said let's go. They said only 10 minutes. I said, ok I can wait for 10 minutes but I need to repark my car! I'll wait here. But in the end I was waiting for 40 minutes. They were waiting till the end of event, and even though I was so upset I didn't have the heart to just leave. It's an absurd situation and I didn't know the people well and I know it was my car but still I didn't say let's go if you want to go home with me. I usually tell people what I think so I thing this situation triggered me. I keep thing about it qnd if it was another way around they would never wait for me that long. I want to change it, I wish I just drove away because they don.mt appreciate it. They've already forgotten about the situation but I can't. I keep thinking about it, I can't eat, sleep or study. I don't know what's gling on with me, I just feel like I've disappointed myself- I just waited for the people that would never do anything good for me. Never. They didn't even properly say thank you in the end. I feel so sorry for myself because I always help others, and they never help me. I feel like I ruined my life or my exams because I think about this all the ime and I can't study. Why did I wait for that people? I should had just left and not care about them. I feel so used but the worst thing is, I feel like I've really disappointed myself. I don't want to do good stuff for the people that can't even get what I did for them. Please help me how to get ocer it