How do you get rid of your insecurities when it comes to being unable to trust people? In every past…

How do you get rid of your insecurities when it comes to being unable to trust people? In every past relationship I have been cheated on and I don't know how to trust my boyfriend because of my past. He has been faithful and honest and trustworthy but I can't trust anyone because I worry that its going to happen again. And because of that I feel I'm obsessive and I keep pushing him away. what can I do to help cope with or get rid of my insecurities?