I’m the same. I can’t cope with it. Sometimes I’ll spend hours, even days, replaying it in my mind, trying to figure out why they said what they did. It makes me feel sick with worry. I wish I had an answer for you, but you have asked a good question!
Basically, when people tell you not to take it personally, they’re essentially asking you to don’t validate what you are your feelings, which can feel impossible because you’re already experiencing them.
I’m really sensitive too. Sometimes, even if it’s not rejection, I interpret it that way. If a friend doesn’t respond how I expect, I worry they’re disgusted by me and feel ashamed. It’s tough to deal with, especially because it makes me feel unsafe around people, even friends. I’m sorry you’re dealing with this too. Sending you love.