OCD HELP

Okay to beging with i am an 18 year old gay male not sure thats relevant but every little helps. I have had Intrusive thoughts from the back end of last year to now i dont know why or how they started but i have had alot of them and it varies so i would have Murder, Pedophilia, death. suicide, rape, incest and alot more just to name a few. i would have a thought it would last a while then i would think i would rather have this thought than that thought then i do get that thought and think this is hard i want that thought insteaad of this thought. i have never been attracted to children i have always like older men im 18 now that hasnt changed but im scared its going to happen overnight or im going to change.People say dont fight these thoughts it will make it worse i should just let them happen but then i think if i do that will i chnage or anything? pus when i first got the thoguths i was scared i cried but when they come back i dont feel the same why?