A tough situation and one that resonated with me. I have posted before about the problems in my marriage and the awful behaviours of both of us (began as a sleazy affair, moved straight to cohabitation, blended families - utter shit show of toxicity and jealousy (her) and assholery (me))
Many years later we are still together in a sexless marriage. For a period I wanted sex, my wife did not - well not with me. Now I don't with her either as there is no love left.
I tried to leave but my wife pointed out that I'd ruin her standard of living. I'd ruin mine as well but I'd pay that price. Then she was seriously ill. Mostly recovered now, working full-time but hates her job and wants to retire early.
I am her support person- she even said to me that she needs a person to offload to about work, her family and so on and that this could be someone else but as she wouldn't meet anyone I am it.
In essence I feel like the choice is to increase my happiness (live alone, do hobbies I like, be single, provide more care and time for my kids) at the expense of hers or do my best to be noble in some fucked up way.
It isn't always easy to put your needs first.