My partner is an arsehole

A few months ago, my partner of 9 years (father of our two children) decided that he thinks we are more like friends. It was totally out of the blue, since then we have been “trying” to figure things out. However over the last month or so he has become the most insanely selfish human being, he’s always had a touch of a selfish streak but this is on a new level. An example- a few weeks ago I stayed over with our son in hospital, on the back of two hours sleep I went out to my 12 hour night shift, then looked after our son at home the next morning, managed to get another three hours of sleep, later on, I put the kids to bed and went downstairs to find him cooking himself dinner, didn’t even ask me if I wanted anything. Another time he went food shopping and only bought things for himself! What the hell. Anyways, I’ve tried to call him out and that hasn’t worked so now I’m starting to bring myself down to his level, which is something I don’t want to do, it’s petty, but he’s forcing me into it. How do I get myself out of this horrible situation. Side note- I don’t have anywhere else to go with the kids and currently we own the house together so can’t afford anywhere else either. I’ve told him he should leave for a bit, but he’s still here and I have no idea why cause he’s clearly not enjoying it.