I hope that you're taking some time away from H's madness to center yourself and S. Remember, this is HIS mess and sucking everyone in.
I agree with many here about setting boundaries, and that perhaps this is the "crisis" that will end the CRISIS. Regardless, you and S need it now, the separation, to focus on getting you healthy and happy and focusing on S's health. Right now, H is not a H or father....he's in his own storm, and your job is not to stop the storm, but to take shelter from it while you can.
I don't know what this means for you. You can detach more while living with him, get focused more on your life, or you can ask him to leave. Right now, he has the comfort of "choosing" something that should NOT be a choice in a M. He said a few things that are concerning...that you take care of him, that he loves you, but wants the "friend" in OW, etc. JokerMan is right, I think MLCers and others like having the spouse hanging on...the very people they are "running away" from. I think you need to pull the comfort of this dual life out for him.
As Ellie said, no matter what level of detachment you employ, do it in a cool, self-confident, self-preserving way....not as punishment. Ultimately, it has to come off as "this is good for both of us...you are sorting things out in life, and need space, and I need distance b/c it's so toxic for me and our family." Do it with a smile, no emotions, as a friend. H is just your friend now, one in a VERY bad spot. The best you can do is watch this from afar, in a safe location.
When you detach, you are still friendly, just not being his W. Actions have consequences. As Ellie said, you patient grace was a good tactic before, but now it needs to be different, mostly for your own health/sanity. When you detach, grow strong, for yourself. Look how strong and powerful you have been....without worrying about H and all his games, think how much more so you can be.
Get healthy, fit and strong. It will make you feel good, mind and body. Get financially saavy....it will make you feel empowered. Focus on work and S's health, it will make you feel valuable and needed. Get out with friends at least once a week....it will make you feel fun and loved.
You are all of these things, now start living it.
H's life is spinning now....that doesn't mean that yours needs to be sacraficed in the MLC crisis...take it back. Live it fully.