I haven't read the entire thread, but god, you poor thing. I really do feel for you. I too have a history of sexual abuse as a child. I deeply understand how this shows up in our relationships. I too was married to a man with fucked up fetishes and kinks that developed over the years due to his 'evolving' porn addiction. I don't know if you have that issue in your marriage.
Ours became an entirely sexless marriage the last 8-9 years of it. We divorced (for a terrible, terrible, terrible reason which I won't delve into now). I'm at total peace now. Whether I ever have sex again or not is no longer occupying a lot of space in my head. Now that I'm liberated (yes, really, it has been a liberation!), I'm just so damn happy to be out of that dark, oxygen-sucking, soul destroying marriage that I was propping up.
We choose our husbands. They choose to become assholes over the years. And when that happens, you do everything you can to just release yourself from that misery.
Be careful of this other guy. He sounds like he can smell your vulnerability a mile off. If he were a good man, really worth shagging, he wouldn't be married and behaving this way. He'd be approaching you with decency. Never ever ever settle for less than decency, OP. Promise yourself that. He's not a nice guy or a good man, your friend's husband. And his actions are proof of this.
What they do for you, they'll do to you. Good people don't blow up their families in this way. Shitty people lacking ethics do this. I know you're lonely and I totally get where you're at, wanting to just have some skyrockets in flight (I've been there!). But don't be that person. And don't allow yourself to be manipulated by that kind of person. Masturbate to him but do.not. fuck him. He sounds very overwhelming, domineering, and totally lacks morals and boundaries. You're very, very vulnerable. Set your boundaries... do this for you. And really, honestly think about extricating yourself from this dead marriage. Put all men aside and just make a real plan to progress in your life. You have one shot at this thing called being alive. Forget the men for now (they're not the solution right now) and think about what you truly need. You may WANT to have bed breaking sex with this guy. I can totally understand your reasons. But it's so not what you need.
Write down what you need, after a good sleep and in a quiet space.