tried to end it but he won't accept it

Hi, My partner has ADD, we have 2 small children together. Things are bad, all the usual stuff really and now I'm at breaking point and feel like theres something screaming inside me "RUN!" But as I said we have 2 children and just "running" is not an option. A couple of weeks ago I ended our relationship but he literally wouldn't accept it. He said the only way he would go is if he could take the older child with him (we have 2 boys very close in age who absolutely adore each other so I'm sure you can imagine this would not be the best thing for them) He said he wasn't happy either (obviously as I'm the partner of someone with ADD I am automatically a nag) but that he couldn't live without the kids (fair enough neither could I) But this leaves us in this weird situation where neither of us wants to be without the kids and he says he wants to work on things and promised all this stuff which he hasn't done (it really is amazing how convincing he is when he lies and I have been with him for 8 years now you would think I would know the signs!?) and I just feel like now I am back to square one and feeling like a complete idiot for trusting him. Surely there is a way out of this, I just don't know what to do anymore?? My main reason is the children - I don't want them growing up in this disordered household with arguing all the time and a mummy who is always annoyed with daddy and a dad that doesn't listen to anything being said. But then breaking up isn't ideal for them either. And I don't want to break his heart by taking his children away from him, he doesn't even have anywhere he could go (family all overseas)