Effects on adults of child sexual abuse?

When I was about 5 yes old I was at an uncles house when my 18 yr old male cousin convinced me to play a round of hide and seek. He got me alone in a room and there he went on to perform oral on me before trying to convince me to do the same to him. Thankfully I was able to leave the room. I said nothing about this until I was about 10 years old. The authorities where not contacted because I had asked for that not to happen. All I wanted was for it to go away. I remember my mother on the phone screaming at my cousin saying that he had 24 hours to leave town or we would call the police. He did and I only ever saw him once since then. We never got me any help for it but I was able to talk to my mom about it whenever i wanted. Of course I hardly brought ever it up. I am now 26 & while everyone thought it had had no effect on me, including myself, it's now that I feel it is starting to get to me. I've been thinking about it alot over the last 5 years. During the last 5 years I've also become very isolated, pushed away all friends, depressed and had significant weight gain. I've also never had a romantic relationship. I've had many male friends before but for some reason I've always been scared/nervous of physical contact like that but never thought anything of it. Just dismissed it. Last night I spoke to my dad about it for the first time & I had a panic attack remembering. Could what happened be effecting me now or is it something else? Is this normal? What should I do?