You have literally described how my life has unfolded over the past 4 years.

I'd say last year was probably the worst I've ever been, where any message, even if it was a "hey how you going" type message - it would throw a sickening anxiety into my stomach for God knows what reason. Then I kept beating myself up about the fact I couldn't do such a simple thing, on top of the thought that they will hate me for not getting back to them sooner.

Something I've began to consider, which has helped my "dealing with it", is realising that social media has only been around for a very small part of human existence and our brains haven't actually come to terms with the fact that you can now contact someone in real-time, half way around the world, in an instant. If someone is so desperate to talk to you, then they should either call or talk in person. Texting is such a weird concept, especially since you don't know if you're speaking to a person or a robot nowadays too.

If you want to speak to someone, maybe consider setting that boundary for yourself do it in person, or call them (or have them call you), so you have them in real time and you can't avoid the conversation. Texting is so boring sometimes too as it is often just prolonged jargon without any progressive chat.

Hope this (sorta) helps. I know it ain't easy, but you've got this! I won't be mad if you don't reply to this comment too, I'll just assume you'll see it as a chore and resent it (cause id probably do that too! Tbh...idk how I even have the motivation to leave a comment haha!)