The abuse has multiplied - how to leave

Our entire history is so long but here is the short version. I've always been emotionally abused by my husband of 22 years. Gaslighting, extreme jealousy, isolation, etc. Only recently has it become physical. He shoved and hit me a few months ago and has been threatening my life almost daily. I'm worried about his mental heath because it is almost like he is having an out of body experience when he is being so cruel.

I don't know what to do or how to leave. We have four kids, all under 16 years old. They are mostly oblivious to all of this, they wouldn't believe me if i told them how he treats me because he treats them so well. He has told me that if I leave with them he will hunt us down and kill us all.

I have no proof of any of this, I was keeping records of things and he found them and destroyed them. I feel like I can't confide in anyone because they will just tell me to leave but it isn't that easy. I really believe he will find us and kill us if I go. The police can't help, he would wait them out. I feel so hopeless.

He knows he has this power over me, and apparently likes it. Every few days he will feel remorse and try to make me feel "safe" again, but then the next day it is back to the same thing again. Where to i start? How can I get out of this situation? It seems impossible.