soooooo bjs

So a little over a year ago a had a horrible boyfriend who would force me and blackmail me to give him a blowjob. Now I am with someone else and we've been together for a while and he asked me if I was comfortable doing it to him and I said no and although I know it isn't a deal breaker for him I still feel horrible because I want to be able to pleasure him because he pleasures me but I just can't, I have ptsd. He knows what happened with my previous boyfriend so I think he understands but it doesn't change the fact that I don't want to make it seem like I don't care about pleasuring him. What do I do I need help.