My stepson is the worst

The title says it all....

He is almost 8 and has ADHD, ODD, and sensory disorder. He is on medication and in therapy- has been for a couple years. But he is only getting worse. He is violent, throws tantrums like nothing I have ever seen, he flips furniture, threatens people, hits and kicks his teachers, they have to remove him from class multiple times a week. He has been lying, not listening, he scratched my car because he as mad. I am losing it.

No one gives him consequences and everyone just gives him whatever he wants so they dont have to deal with him. I am actually thinking about leaving because i have a 6 month old daughter and I do not want her thinking this behavior is ok. His dad just wont get on the same page as me and says he is his son so he'll raise him how he thinks he should.

Does anyone have tips? I feel like we have tried everything, so it seems like there is no hope and I am sincerely worried about my daughter growing up around him.

Thanks in advance