This is very similar to a situation my best friend was in until last year. His dad is much like yours, very childish in behavior and flips for absolutely no reason, only cares about himself, but also very manipulative and can fake nice to people outside of the family. My friend had to protect his mother and sister from physical and sexual abuse multiple times, so much like you he felt he could not leave and had set aside his life to keep them safe. Only recently has he been able to start his life. He helped his sister finish college so she could leave, then managed to convince his mom to leave the state to go live with other family members and file for divorce from afar where she is safe.

If you and your mom don't have the option of leaving the state like my friend's mom did, I found this site on Google for you: https://victims.ca.gov/victims/issues/domesticviolence/
There's tips and general info on how you can get out of that situation. It may only be verbal abuse now, but it's still a horrible situation and could turn physical so the sooner the better.

As for your issues with anxiety/rage and therapy not working, it's possible you need to try to find another therapist. From what you described it sounds like you want a therapist who is more engaging, which has definitely been an issue for me too.