Potentially lovely, perpetually human

I used to have it really bad, and I no longer do.

Note: my reaction to meltdowns is isolation, not confrontation. And I don't really get angry much in general. But even so, I've probably been unfair to people in other ways because of RSD.

My gut reaction advice was simply "actually ask your friends for reassurance". Just admit you're feeling insecure and request a little extra support, especially before it gets really bad. But then I realised this was very incomplete advice because of one specific reason...

RSD is "triggered by perceived or actual rejection, criticism, or disapproval". Those are actually VERY different, and so is the advice.

If you're logically pretty sure your friends don't hate you or are annoyed at you:

If someone seems to be ignoring you, stop yourself from trying to "fix" it by being more entertaining or fun. You're making it worse for yourself when they don't react.

(Also don't try to force someone to cheer someone up because you can't handle them being sad around you.)

Gently ask for reassurance. "I'm feeling a little needy right now, can you respond to the thing I shared?"

Find out why you get the rejection vibe. Chances are they're tired or busy or whatever, and it has nothing to do with you.

You can couch it in an apology or question if you feel guilty. "Sorry, are you busy?" "How are feeling today? You seem quiet." (This is also a good way to respect their time and energy, at the same time as you reassure yourself.)

IMPORTANT: Do not make demands! Friends do not owe you constant validation.

Do your very best to avoid blaming them for your feelings. Don't say "you're being very short right now and it's triggering my RSD". Instead admit you have need for more reassurance.

Again, remind yourself it probably has nothing to do with you. You can also ask other friends for input and reassurance to try to figure out if it's all in your head. Outsource your validation.

Over time you will hopefully get more secure.

If you're dealing with actual rejection:

Accept their rejection. Always. Their consent is more important than your feelings. Even if the feelings really suck.

Never ever punish them for their rejection.

Aka, don't demand a justification, don't get angry or upset at them, don't guilt them. If you have gotten an actual rejection, the best thing is probably to remove yourself from the situation, especially if you're having a big emotional response.

Your feelings are YOUR responsibility.

If you make it clear that it isn't safe to reject you, then consent means nothing. You will probably trample over boundaries even if you don't mean to or realise.

Seek emotional support ELSEWHERE. Talk to a friend. Do self-soothing. Have a good cry if you need to, or punch some pillows - just don't do it at the person who rejected you.

Basically:

If you're facing actual rejection, I'm sorry, but you are in fact just going to have to learn to deal with it. Everyone has to. It sucks.

If you think your brain is just sabotaging you, reach out for reassurance. But remember that not everyone is able to give you that at all times, and you NEED to have more than one person to rely on.

Work on emotional regulation in general. That's a bigger topic I can't cover, but it will help.

PS: This is assuming your friends are decent people who want what's best for you. If someone is actually being an asshole, I'm not saying you should excuse or tolerate it. (Getting a second opinion can help there too.)

PPS: Same goes for unwarranted criticism or disapproval. When I talk about respecting rejection, I mean when someone does want to hang out, or you got fired or something. But the advice to simply remove yourself from the situation works for both.

PPPS: Remind yourself that someone who's liked by everyone is probably very bland, or extremely people-pleasing. You don't actually want everyone's approval. Focus on the people whose opinions you respect and care about.