Sexual assault help please

I was sexually assaulted in Feb. of 2018 and it’s still affecting me. Every time a guy likes me now, I push them away even if I’m interested. I still cry and feel dirty. And sometimes I have nightmares about it. Last year I tried going on a dates just to get over it. But both times I felt awkward and scared. And I felt bad because it wasn’t those guys fault at all and I know not every guy is going to do something like that. And now I can’t even work up the courage to accept meeting up or anything. I don’t know what to do. I want to be able to date and be carefree again. It’s too hard to bring up with a someone I don’t really know. So I can’t even explain to a new guy why I’m so shy and hesitant. But if I don’t give any explanation they just think I’m blowing them off for no reason. Please help.