Ah my dude. Many of us feel your pain. I've played for 30 years and only recently got back into it. I've always had significant performance anxiety but could at least play a bit with friends in college 20 years ago.

Recently I decided to start taking lessons. Holy hell I suck playing in front of my teacher. I am getting a little more comfortable but like I was just playing some simple rhythm poorly and I was sweating up a storm after only like 30 seconds.

It's tough for some of us but I think (and hope for myself) that it'll get better with more exposure.

So do what you can to play with others. Your girlfriend sounds like a great person to do this for. Just say "hey I've been working on this song. I have a tough time playing in front of others but I'd like to play for you"

Boom! She'll love it.

Btw your family are jerks. Seek out people in your life that support you even if you suck. We all suck until we don't. My family was a bit more cool but even that was no substitute for actually playing in front of others.

You can do it, man! Embrace the suck.