I hate being a step-mom

Like hate it with my all. I don’t even know where to start. My husbands ex wife is constantly taking advantage of me. Sends their sonto my house on the bus after school almost everyday. Even though she’s home. This wouldn’t be an issue except he never listens and he’s disrespectful towards me. 5% of the time there are no issues. He’s been going to therapy for years. He will probably have to continue into adulthood because his mother thinks a pill is going to fix everything. I have asked multiple times to go to therapy with him to see how to improve our dynamic and I am always shut down. I feel like my husband doesn’t fight for us to all feel like a family because he’s never going to stand up to his ex wife. I HATE being alone with the little boy. It’s always drama. Now I’m having another baby in three weeks and I honest to God am resenting my husband. He doesn’t take anything I say seriously. I feel like he’s content with how things are and it disgusts me. He knows I’m treated poorly but he finds comfort in the fact that he’s not screaming in my face anymore. I guess I find some comfort in that too. I guess I’m just over it. I have to go.....because he will be off the bus soon and it’s my job to make sure he does his schoolwork. He won’t listen but I guess I’ll try. I know I sound crazy....but if I had known it was going to be like this for me and my children I would have never married him. I hate that😢if you got this far....thanks