I don't think you have 'screwed it all up'. He's the one who did that, who took your power away. It sounds to me as if he 'seduced' you into the sexual relationship he wanted instead of sitting you down before you became truly emotionally involved and discussing his kinks and allowing you to make a more, shall we say, rational decision. If he had, you might very well have said 'No, that's not for me' and ended the relationship. I know I would have. Instead he hid the real reason for his ED and let you think, as a 'good partner', that you needed to 'do it his way' so he could get off. Did he repay you in kind with the loving and tender sex you needed? No. Or at least not enough that you felt it was a 'fair deal'. Instead, he's made you feel as if you are responsible for keeping him 'satisfied' to the neglect of your own well being. And to make you feel guilty if you resent it.
Discuss it with your therapist, but at this point I think you need to STOP talking to him about his kinks and your desires, and that any physical contact is off the table, for now. All it's going to do is confuse you and allow him to gaslight you or play on your emotions. Instead, I think you need to concentrate (with your therapist) on truly understanding that you have an absolute right to what YOU need physically and emotionally. And that you also have an absolute right NOT to do anything that does not leave you feeling loved and respected. That you are NOT responsible for his satisfaction at the expense of your well being. That sex in the context of a relationship is not a 'transaction'. It's not 'you must do this first and then I'll do that'. It is supposed to be a joyous and unselfish coming together in mutual love and respect. And that is NOT what you have.
I also think it wouldn't hurt for you to see a divorce solicitor. Not to start anything. But you say things are 'too entwined' to divorce. Unless and until you have laid your finances (or whatever it is that makes you say that) on the table and allowed a solicitor to advise you as to exactly how you would be able to 'dis-entwine' and what you might end up with, can you truly say that. I think it's fear that is holding you back. At the very least, you will then be making a decision in knowledge and not out of fear.
You've lived with this shit far too long and I think he's done a great deal to make you feel you need to cater to his kinks. You don't. And he'll never make you feel loved and valued, physically, in the way you want to feel.