Today it all came out

2 months ago I got my first actual job. I only work 2 days a week, but I still feel terrible every time I have to go to work. I don't know if I "have" anxiety, I've never really gotten any help, but I've had a few breakdowns and I've always been a bit unstable emotionally.

The place I worked at is good, and coworkers are nice, but I still hate it. They wanted to give me more hours and I couldn't say no, because I don't want to be judged or anything. I mean, I barely work. Today I had to work 12 hours. Tomorrow too. I have been terrified of going to work the last few days, and I can't really explain why. In the last moment right before going to work, I texted my boss that I quit. I don't have a contract or anything with them, so I stayed home. They wanted me to come take my 2 last shifts to end it nicely, and they were fine with me quitting. But I couldn't stand the thought of being there. So now I've just said no, and they don't have anyone to cover me and take my shifts. But I just can't go.

I'm terrified, angry at myself, and I just feel like a coward and useless.