How did you finally do it?

Is the ending of a marriage always miserable only? There are many days I’m content - happy that we are together and having the comfort of having gone through so much together (we have been together 13 years) And then there are days…..I’m just..SO exhausted by being with him. I’m not happy. Overall, I would say I’m a 4/10 for happiness at any given time. On many occasions, I’ve brought up the subject that we just need to get a divorce. We haven’t been on the same page in a long time. He refuses to entertain the thought. He has told me he will tell the kids I am a bad mother and that I broke up the family. This makes me stay. Then I stay and we have decent days. Once in a while, we’ll have a stretch of good days. And then mostly, little by little, we grow slightly further apart each day. We have four kids: 7, 5, 2 and 1 year old. For those who have left a marriage with kids involved, how did you finally do it? How did the kids fare? To be clear: I want a divorce. I would rather be by myself than with him.