Sexual Abuse Support Group
Sexual abuse is a relative cultural term used to describe sexual relations and behavior between two or more parties which are considered criminally and/or morally offensive. Different types of sexual abuse involve: Non-consensual, forced physical sexual behavior such as rape, incest or sexual assault, or psychological forms of abuse, such as verbal sexual behavior or...

Just tell him - "Hey, I'm a little anxious about sex and stuff because I had some bad things happen to me when I was young and I don't know how it's going to affect me." He will need to know what to do if you do have a bad reaction - he may feel scared or guilty, so you have tell him how you'd want him to handle it.
Just remember, this is way too common a thing that happens to people, so don't feel like a freak. Lots of us go on and have long-term relationships with partners who are fine and understanding. You'd be surprised how often it happens to men too, so you never know what he might have in his own past.
I hate the expression "damaged goods". We are not "GOODS", we are human beings. And we were hurt by other human beings. Your sexuality belongs to you. It's not something that you "give" to your partner - it's yours.