My Dominant Son

I need to get this off of my chest and tell someone. My son is very dominant and treats girls like whores, including me. He needs help, and i dont know how to handle it. Ive talked to him multiple times about it but he wont listen. My son is 25 years old and is a grown man. One day he caught me in a vulnerable state and i gave him a blowjob. He also took a video which i was unaware of at the time. I said it was a one time thing. However, now when he is in the mood, he will come up to me and whip out his horse cock. I think since he so big , thats what gives him his mindset. He will smack me in the face with his cock and call me names. He calls me his big titted cocksucker. I feel so embaressed, he calls me it even in public or when im with my friends. I feel that i cant do much because he has threatened about blackmailing me. He tells my friends that i love sucking my sons big dong and that i need my "daily" feeding. I dont know what to do.