Go back to your goals. If you focus on you and getting you healthly then the detaching is absolutely necessary. What may feel a little strange is that maybe he doesn't know what your doing. You have set the boundary yourself but he keeps trying to penetrate the invisible wall.
He will definitely keep trying to cross it. He feels you pulling away and he needs to control you. Believe me it is much scarier in his world everyday than yours so you are part of his self medicating.
If you have chosen door #3 than you need to to tell him it is not your intention to leave your marriage but that you are focusing on you and boundaries for that process are _____. His phone call to find a grocery store? WTF? he doesn't need you for that. Tell him to call his mom. He suffers from depression which you can't fix. REMEMBER CARE ABOUT, NOT CARE FOR.
You can borrow from what I told my wife- that I'll be here working on being happy until she decides this is something she wants to work on. Status quo or old marriage is not on the table anymore for discussion.
My sis has been in therapy and it is helping I can tell. She has more clarity about stuff now. But my sis doesn't have PTSD or depression or a PD. So our (yours and mine) situations are not plain vanilla MLC. As it was put to me my W is vanilla MLC with a few nuts thrown on top. Here we go with nuts again. Nuts and squirrels. Nuts and squirrels.
I find that journaling all these thoughts and feelings you have helps a great deal. Then they are not bouncing around in your head where they can break something, it's very fagile in there right now-think bull in a china shop.
Have a great day!
My goal is to some day be the person my dog thinks I am
