What am I so scared of that I can't just walk out tonight?
I don't know what the answer is for you, but I was afraid that if I walked out and stopped obsessing over what my boyfriend was drinking/doing then I'd have to figure out why I allowed myself to be treated so poorly for so long. And that's hard work.
Walking out the door was like walking out of the darkness and into the light. I should have done it years ago.