My step son has crossed so many lines!

I'm not trying to be the evil step mom. I care very much for him but this child just crosses line after line. He is 15 and bullies my 6 year old. He's broken her toys. Calls her a bitch. Calls me a bitch. Went into me and his dad's bathroom and peed ALL over the floor and then jizzed on the toilet seat. Got into a physical fight with me and broke my arm! Then threatened to kill me. My husband had to call the police and he went running outside with a knife. They saw the knife and tased him. He would sneaks boys and older guys(he's gay). And caught him having sex in me and his dad's bed. Set fire to our shed. Today he broke down the lock on our door and destroyed our room and my daughters room and SMEARED SHIT ALL OVER THE PLACE! I absolutely lost my mind. Not at him but to my husband. My husband is basically lying to my step son right now. He called to make an appointment for a psyche evaluation at a mental hospital for minors. My husband is there right now and they're gonna keep him because when he realized where he was he went absolutely ballistic and they had to restrain him but my husband is sti having to do the intake process. I feel absolutely horrible but at this point it seemed to be our only option.

I don't think he's on drugs. I know his biological mother did heavy drugs when she was pregnant with him and while breastfeeding. Part of why he almost died as a baby. His bio mom is bipolar and schizophrenic.