There's not really a way to 'get over' having a hard time trusting people. After going through high school and well.. just growing up, I have a hard time trusting people, family and friends alike. I've been fucked over too many times. My thing is, I don't hand trust out like candy, you have to earn my trust over time. You'll overcome the trust thing in time. Don't rush to trust sometime just for sex because in the end you might make things worse because you really didn't fully trust them.
Not sure I made sense, hah.