Gay & anxious: a killer combo

I've always dealt with really bad anxiety in my life. As a kid I had selective mutism, an anxiety disorder where I was completely mute in any public setting, including school. For some reason, the idea of talking to people gave me such debilitating anxiety that I just completely froze & couldn't do it. Part of me really wanted to, but I felt, in a sense, trapped in my own head. After years of therapy, I finally got over it when I was 9. I had missed out on years of social skill building and still had trouble making friends, but at least that feeling was finally over. That is, until I realized I was gay. Just the thought of coming out to my family gave me the same irrational feeling of pure terror that I experienced all those years ago. And that still hasn't changed. I'm 24, my parents are super liberal and accepting, and I still have not been able to come out to them. I feel like they don't even know me, like there's this wall up between us and I'm completely powerless. Anyone else with a family like mine would have come out a long time ago, but I just feel like I'm such a weak person. It's not just about coming out either. I get the same feeling when presented with any opportunity to try anything new. I'm still a virgin because any time anyone shows the slightest bit of interest, I get the same mortified feeling and I distance myself. I don't know why I'm like this, and I've never even met anyone else who's like me in this way. I wish I could change, but I honestly don't even know where to begin. I feel like I'm gonna be stuck like this forever.