My one friend makes me spiral

My friend's going through a rough time (didn't graduate because of adhd, can't drive because of anxiety) and I've been doing all I can to be good and support her. We've been together since grade school and created a lot of fantasy worlds together. I volunteered to drive her 30 minutes to her therapy appointment yesterday and at first it felt good to be with her. I told her about my unusually good morning hiking in the woods and finding interesting abandoned things. I sketched in my sketchbook and listened to music while she had her appointment. I was feeling pretty ok for once. Then she wanted to go to Ulta to shop for a friend. I thought we would talk more about the cool things I found in the woods (like several photos of people hanging in frames off branches- bizarre stuff) but she blabbered on about how she was going to send a pink scrunchie to her friend. I drove her there and couldn't understand the appeal of nail polish and makeup but I tried to stay engaged because she was so excited. She tracked down an employee and completely ignored me in her quest for a highlighter or something. I wandered off. I bought the basic skincare I normally buy there and then she wanted to go to Crumbl and Bath and Body Works and I couldn't eat a cookie with her because I'm still struggling with an ED and she knows this and I was thinking about human greed and consumerism and liberalism and capitalism and the bizarre concrete jungle shopping centers are but I didn't say any of my thoughts outloud because she wouldn't relate. I felt like a complete alien. She then wanted to drive to Sephora and Michaels and she was talking about advent calendars and YouTubers and I was thinking about being surrounded by trees just that morning but now I'm just another monkey in a car surrounded by other monkeys in cars and I wanted to throw up. I told her no and I tried to explain what I was feeling but I have a feeling she didn't get it. I told her that the only thing I wanted to do now was lie down in the graveyard in my neighborhood. She said ok and I drove her home and I was so wound up and so very not ok. I instead took a walk in the dark on paths in the small town near my neighborhood. I found a swing and I swung on it until I felt sick. Still not ok. I walked until I was exhausted. Still not ok. I curled up in my car and tried to find validation by searching reddit posts. Still not ok. It is now the next morning and I need to do work but I feel so massively depressed and I'm harrassed by the thought that I should have just starved myself to death when I had the chance years ago because everything since my recovery has not been worth it. I don't know what I want from posting this, I think I just need to get this off my chest because I don't even know anymore. I love my friend but I spiral like this after every hangout.