Anyone else here a stepmom?

This is our 1st child together. My stepson will be 11 when baby is born. I have been in his life since 3 months old.

How did your stepkid(s) react to the new family member?

I honestly am terrified of how stepkid will act. Hes told me he hopes the baby dies inside me or it will hate life like him when it is born. (He doesnt know the sex yet unless baby nama somehow found out and told him. He wanted a sister). Hes violent with his other 1/2 sibling at his moms house. Ive caught him being not so nice to our pets, killing butterflies, throwing rocks at birds.... Hubby does correct/discipline him for his behaviors and what he says then hubby gets yelled at by baby mama because she feels she has a say in our home when she clearly has no control in her own home.

Before lectures start, i know this is not typical behavior for a child. He was in therapy and treatment and his mother stopped it because she didnt like what he was saying about her. He is here in my house every weekend. Hubby is a truck driver, gone all week right now, so we dont we cant get SK during the week. We cant get him help/treatment w/o her consent. Not making excuses. It is what ive learned from playing this bitter baby mama game in and out of court for almost 11 yrs.

So im asking, how do i get SK to adjust and ensure the safety of my baby?