Your wife brings up some very good points, especially about you being beaten black and blue and bloody by your son.
To me, your son's actions are dangerous. Out of control behavior is a sign that the medication is not working. This is a see the doctor ASAP moment. Before he can learn how to effectively manage his anger with the fantastic Triple R's he needs to be in a place where he is calm enough to focus. To be in a good place to make good decisions.
Crucial elements also include getting enough sleep. A rested mind along with the understanding that the medicine is not the complete answer. It stabilizes the brain chemistry, but he has to be actively be part of the solution. Not taking an active effort on his part is like canoeing without an oar. You get down the the river but it's out of your control.
His behavior has escalated beyond your control. Does he see a psychiatrist for his medication levels? The good ones know how different drugs interact and what might be most effective for your son. And many times it's trial and error until the right mix is found.
On another point, your younger son of tender years watches and learns. Those little eyes watch to see if you will protect him (9 years old), keep him in a safe place along with what is and isn't appropriate behavior.
This is beyond the divorce, whether or not parents support one another. It's a kid who's brain is whirling beyond control. Who knows, he may be sacrificing himself emotionally. As long as he acts out aggressively you and your wife have to act as a team.
Finding the right combination of medications, counseling (for him and you and your wife together or individually), enough rest, learning the appropriate coping skills will all help him move forward in a positive manner.
