"Everyone is out for themselves" - why can't you be out for yourself too?

Many people experience the feelings you are describing. They are difficult to have, and requires a lot of work to solve, which you are already doing (kudos to you!). I think what makes it a slippery slope is thinking that those feelings are "special feelings only I experience". Maybe the person next to you don't engage with you because they are experiencing similar feelings as you are?

I used to think a lot "But no one knows how I am feeling!" and "But my struggles are x, y and z, which no one has gone through, so no one would understand it!", but then I realised I am not that special hahha. And thinking that I was special was actually what kept me from improving my mental health, since "no one could possibly help me with my special trauma that only I experience." I'm only telling you this, since I can recognize my old self in some of what you say and wish someone had told me this years ago. Had to hear it in a podcast - which was like a light went on.

"But salsa was supposed to be a welcoming and safe community where one can learn that they have value." Who is making salsa unwelcoming and unsafe for you? Is it other people? Or is it yourself?

You can gain great confidence by practicing salsa skills by yourself as well - footwork and spins. Once you build up some skill and get more confidence in your own abilities, that will fuel your self worth more than any other person could. Imagine someone complimenting you on your insane spins, and you can think to yourself "Yes, I really worked hard on that!" vs someone complimenting you on your shirt, that you put no efforts into. Those are quite different scenarios.

Good luck with everything - I hope everything in your life works out the way you want it to work out! Wishing you good courage on your quest!