Why do I want to feel bad?

Hi, I’m 16m. I have a tendency to overthink and overanalyse everything I’m doing, leading me to hate myself and be completely useless in any social situation.
It’s come on fairly slowly. I think I’ve always been like this in some sense, but I can’t escape my own head anymore. I hate the way I speak, walk, act, anything really. I overthink what I’m going to say so many times, that I barely say anything anymore, would rather die in a hole, than have someone judge me. Then, I’ll worry I’m too quiet, look too awkward, and constantly argue with myself in my head. Even talking with my best friends feels alien now.
It leads to me spiralling. I think of everything I’ve ever done wrong, all my flaws, bad though upon bad thought. They build up in my mind until I want to physically tear my brain out, to feel a quiet for a moment.
But the worst part, is I know how to feel better. I just have to distract myself, try to push the thoughts away. But, I can’t bring myself to, and I think on some level, I enjoy feeling this way, even now as I’m writing this, I take some sick pleasure in hating myself. I don’t know how to stop it. I can feel it getting worse. I’m spiralling more and more. I just want it to stop.