How close are you to the step kids? If you can get therapy and separate your love for him into a business arrangement that might work. But you need to know it’s over, set ground rules, get money from him and make a plan for yourself in case you decide to move out. He doesn’t need to know your plans. Hope that helps. Oh and men are jerks! Don’t feel guilty either living there until YOU are financially stable to make another choice

He probably won't change his mind,and it sounds like you're still in love with him.
You know the answer - you need to move.
However, with kids, it's not that easy. And there are financial reasons to stay as well, by the sound of it.
I've been separated under one roof with my ex close to two years now. It's not great - he was controlling during the marriage, and still tries to control me when he can now. I am stuck until we settle the property, as there is a terrible rental crisis where we live, so I'm stuck financially.
If you can afford to, move out as soon as you can.
It's hard to shift into a new space mentally, I understand. It's scary. But you know you need to do this. You are very smart and aware of the situation you're in. You'll be thanking yourself afterward, believe me. A better life is waiting...