Had a girl do this to me once. I was scared shitless and always worried she might actually do something.
She regularly pulled stunts like kerosene, all out, grabbing knives etc. I always had to stop her because I was convinced she might end up doing something in the spur of the moment.
When covid happened, I had no choice but to leave. Got the same threats again. Only this time I had no choice, so I told her I cant do anything and left. Initially she kept threatening me with the same stuff, but its now been 5 years and I am not even in touch with her anymore.
It was scary at first, but I have to say. Leaving was the best decision I ever made. It is never okay to stay with someone toxic who keeps you tied using threats.
Life is too short. You’re not a side character in someone elses life.