How do I leave my husband?

This might seem silly but I don’t really know how to leave.

I could stay with my mom and sister, but what about the bills? What about our son in 3rd grade who has a room at our house?

He won’t leave. I don’t really know what to do. I am over it. I’m pregnant with our second but I can’t take it anymore. He is the retaliation type and would probably talk bad about me to our son (which speaks volumes on the kind of man I married) but any advice is greatly appreciated.