I Never Thought I Could Be So Weak

I dont even know where to begin. Im 52 white female I have been having an affair with my husband’s cousin who is black, 55, who’ll I call J. Of course no one knows of our affair. Now, my husband, 64, goes and introduces his cousin to a good friend of mine.
See, there are two problems, one being J lives in the apt above ours. The next is, Im fucking falling Love with J and he fucking knows it. Yet, I know he has my friend upstairs and knowing him, he's fucking the life out of her and Im so fucking mad and jealous and I cant do or say shit about it. The worst part is she being my best friend, I have to give her my ear during our girl’s talk and listen to her boast and brag about nice he is or how nasty and kinky her man is. Of course the same unique things he did to me, she was getting the same treatment. Like J loved to suck my toes and feet, during sex. What J, really loves. He loved sniffing, licking and enjoying my damp hairy armpits. The not knowing Im in love with her man. At times I want to slap the make-up off her face.
There's way more but that's the meat of it. The other fucked up thing is, he knows he has me. He knows he can fuck me any damn time, and anywhere he pleases. That is the control this guy has over me now and he knows it.
I don’t what the hell to do.