stevie74,
"I know financially I would be better off without him"
Reason one for him to leave
"I earn double his salary p/t so money's not an issue".
Good. He is still financially responsible for his children though, you may need to seek legal advice on that issue as well.
"Mentally I would be happier".
Second good reason for him to leave.
"I've asked him to leave many times but he refuses, say's he won't leave his girls unless it's in a wooden box".
Emotional blackmail towards you using them as a weapon. You need legal advice and fast.
"I've tried to reason with him, set ultimatums etc and it's better for a few weeks then it all reverts".
The problem with ultimatums (and I think you have given him an ulitimatum more than once) is that you must follow it through fully. He has seen that you have not done this properly and any further ultimatum you therefore give is laughed at. He knows you are too weak to stand up to him. He has done a fine job of pulling you down with him.
"He changes everything round so that i'm to blame and at times I feel like i've gone mad and maybe it is me".
He is very good at manipulating and blaming you, it is not you at all. Its his way of assuaging his own guilt. He has the issues and they are his to deal with. You cannot yourself rescue him and save him from his demons.
"I don't want the waltons but close would be good".
You will not get that with him at all, he will just cause you more emotional anguish. Don't hang in there in the forlorn hopes he'll somehow change for the better.
"I feel like i'm a crap mom for keeping him around but even when asked he won't leave..."
Get legal advice, make him see that you are deadly serious and that you have had enough.
"Me & the girls can be having a great day, as soon as he comes home it's all topsy turvy".
I'm not surprised at all to see that it goes pear shaped when he comes home him acting the way he does with your good self.
"He blames his past for the way he is as he was abused by his father but says he doesn't need help".
Yet another excuse. He's wrong there, he does need counselling and to also stick with it but you cannot help him realise this. Only he can. You cannot save someone who ultimately does not want to be saved. For your sake and your childrens' you must act. They cannot ignore what is happening around them at home.
"I made this a condition of his moving with me to a new apartment so he got councelling, went once and didnt reattend, of course by which stage he'd moved in and now wont leave. i dont see why I should walk out of the home, i know its rented and in my name but its the home i've tried to make for me and the girls".
He broke one of the conditions you set. A mistake you made here was to obligate him go there for your own self. He needed to go for his own self, no -one else. The tenancy is in your sole name, action here can be taken.
"God i'm pathetic - I could make excuses for him all day not that he needs help there, he's great with excuses!"
Such troubled people are great at making excuses, you do not need to make further excuses for him. You are not pathetic at all - you just need to find a way out of this mess and it will get more messy for you and your children the longer you stay. I cannot imagine he will make it easy for you to get shot of him, he will make things awkward for you at every opportunity.
"Thanks for all the comments. I know I can do better"
Correct!!!
"I just don't know how to make it right and how to make him go"
See above suggestions.