How do you get the strength to leave?

i’ve been in a relationship for almost four years & my boyfriend is extremely verbally abusive and sometimes physically. He’s in therapy but it’s been years of therapy and nothing has changed. He holds incredibly narcissistic values and rarely takes fault for his actions. Anything he does has to be shared with me because he feels like he’s never fully at fault or he’s in the clear because he feels like if I upset him, I started it so it’s actually my fault for him snapping. I obviously know it’s not a healthy relationship and If you’re going to say “just leave” I will report the comments. I’m asking for genuine advice from people who have been in tough relationships