i dont know why dont you try rejection therapy or something, try the 100 days of rejection program. basically every day go outside of your comfort zone and attempt to be rejected.
walk up to a table in a coffee shop where theres someone sitting, maybe someone alone on their phone or something, ask, "Hey is this seat taken? Mind if i sit here?". Try to talk to them. You'll probably scare them off and feel like a creep and a weirdo. But you'll still be alive right? Will anything really bad have actually happened? Nah man.
Keep at it. Find different ways to be rejected. Eventually, you'll get over this ridiculous fear you're harboring
i dunno man I'm trying to be positive and shit but I dont know how to help you tbh lol