I’ve had several girlfriends with this issue. In a relationship, what has always worked is to let her touch me and then slowly and patiently work on touching her back. I don’t just mean this in the sexual application, I mean for anything as small as holding her hand or resting her head on my shoulder.
As far as regular day-to-day stuff, I see them get very good at avoiding contact. If you learn to lean away from people and show discomfort with your body language, it’s pretty easy to keep people off. Saying no to a hug from a friend/relative is the only really awkward part, but people generally understand.
If you want to get over this fear, find an SO and/or friends you can trust and work on slowly becoming more comfortable with it. You’ll find that it’s not as scary as it seems, and it can be overcome.
Despite the SA, I’m confident you can change your ways if you wish to. On that note, I offer whatever help we can provide as you heal. Welcome to the collective, we’re glad to have you.