Male sexual desire- why is it so strong and dangerous

[Married guy 29]

I’m a good guy that has never done any sexual acts that are illegal and I’ve never hurt or assaulted anyone. So why do I get turned on by sexual taboo like forced sex, forced sex or sex with a sleeping step sisters, and worst of all rape. I know it is wrong and a horrible reality in this world, but when I watch a movie with a rape / molestation scene I get a boner. I know it is wrong a will never acts on these thoughts but is this normal to get horney at the thought of rape? Is it the evolution of man to have urges for sex  no matter the consequences? Apparently so and if we are not smarter than our primal sexual lust and strong desire of pleasure 

My wife is passed out downstairs and her hot friend is here. We just smoked a cigarette together and now all I can think of is getting her outside again and getting into her pants,. Angain, I won’t and know it is wrong, but I’ll be jerking off to the tohougt of forcing my cock into her pussy while she says no. No, stop, and that hurts are all words that turn me on. Why am I such a sexual monster. My wife was molested as a child and so was I. Is it like being bullied? That if u go through it u are likely to do it later on in life? It’s not illegal to have sick thoughts, it is illegal to act on them. Sometimes when I get bored I decid to jerk off for the pleasure but I don’t use porn so I start fantasizing and when girls don’t get me hard I think of sick thinks like when I was molested and I get horney. As soon as I come if feel horrible for what just got me off, but then I get a Bonner latter in the day and pick up where I left off with the same thoughts. I think I need help and done know where to look for it. I’m not a pedofile, but I’ve been jerking off and thoughts of little girls and boys will come into my head and it makes my orgasmes stronger. I know it is wrong, but what can I do? I’ve thought about chopping my dick off before due to how strong the feelings in my pants get. The more I think of rape / forced sex and fantacies of taboo and down rite illegal acts the mote the thoughts show up in life so I know I should stop the thougts, but then I don’t get hard or horney enough to come and that is one of my greatest pleasures in life so I continue the mental fantasies and feel great pleasure while coming followed by feelings of disparity 

hope this doesn’t scare you. I am not a preditor and would like to stope being aroused by these throughs. Is this normal and how do I get help? I’m scared I’d get the cops called on me if I told a physic that I get aroused by not ok things