Sorry about that - accidentally pressed post too soon.
You have decided to end this relationship. You have given your reasons, and we all agree with you. But even if we didn’t, you can still decide to leave for any reason - honestly.
You are however, doing it for the best reason ever - your children.
Everytime you start guilting yourself over him, “oh he’s a good dad” - reframe it - “does a good dad - not go to counselling, not take medication to sort his mental health out? “Does a good dad - not keep a job, smoke cannabis, let his partner pay for everything? Does a good dad think of his children first and foremost in everything situation? Does your partner?
But even without reminding yourself the why he must leave, the end result is the same, and you need to resolutely focus on the how and when.
I read an interesting article about the difference about guilt and responsibility and how those two things can become mixed up. I’m think if you google it and keep it close to reread when you become confused it would help you keep on track.
It is possible you are in an endless thought loop, and keep returning to the why you should split. It’s a bit like deciding what to cook for dinner, then instead of start cooking it, you’re looking through your cupboards in case you find some other ingredients which mean you should cook something else entirely.