Sorry, that must be a difficult position to be in.
In my opinion it's still the same behavior, just a different angle. I'm a guy and although I don't see the appeal, I don't mind if someone else does those things, it's their life. However, what I don't agree with is doing those things when you share a life with someone else and expecting them to go along with it. It's not like you knew this was the case from the beginning...
There's give and take in a relationship, I'm sure plenty have kinks that are one sided and it's a case of whether the other person is open to those. If not, you don't force the issue because they are not comfortable with it, the kink isn't a shared interest.
What I think is happening here is you are purposely being put in an impossible situation for his own needs to be met. Regardless of the fact that he's talking, working on his behavior and gets upset, doesn't eat or has breakdowns, it's all the same behavior to get what he wants and make you feel like you have no choice.
Why does it work? Because you have empathy, you care about him, like a normal person would but unfortunately some people can manipulate those emotions into making you bend on things that you do not feel comfortable with.
Although he is your husband, he clearly has changed and if he cared as much about you as you do about him, he wouldn't put you in this position. He's emotionally blackmailing you, if you don't fold we won't be friends because I can't bear to be around you if you dare to seek someone else. Control. Jealousy.
You cannot live your life worrying about someone who allows themselves to dip into those depths from something they have created themselves, not eating etc. That's his own issues that he needs to deal with. Similar to those who threaten suicide... it's all guilt tripping, something that shouldn't be on your shoulders.
That right there tells you all you need to know and I bet you any money, should you not conform that behavior will return.
Don't worry about the children, I used to worry about mine, keeping the family together, their life. Mine was abusive, same shit and I've come to realize the family ideal is not always ideal. It's not always the right way for children and they can thrive in a different environment, rather than growing up around behavior like that.
You shouldn't be in a position of living your life a certain way or having sex and pretending to be enthusiastic when you are not and are not comfortable with it.