Having a a hard time expressing my feelings advice???

Iv been dating my bf almost 3 months but iv known him 5 years he was and is my best friend from high school. We lost contact after high school for few years. And some things has happen far as emotional and physically abusive relationship. I use to be a drug addict as well given the relationships. Iv told him this before we started dating. I love him I do but a part of me still has a very hard time expressing my feeling towards him. It’s not him it’s me I’m very cautious. Any advice to help express my feelings more.?