I hear you. It’s not something I can understand easily; my social anxiety isn’t that intense.
I would suggest to you, and others like you, though — if you are going to put yourself in a situation where you must interact with others, such as rp, even selectively, being able to tell people ‘no thank you’ is a place you should push yourself. Yes, it will be hard, god it’ll be hard. But you will not get better without trying, and you’ve already made a huge effort in being a roleplayer at all.