Have a chat with him and be honest and tell him you feel suffocated and like you're paying for everything and don't want to be as involved a step mum as he wants you to be then see what he says.
I can tell you what he will say.
He will convince OP that she has a bad attitude, that she owes him because he is The One, & that she isn't doing enough emotional labour for his kids. He will explain that she is over-sensitive, & badly in the wrong. When she's feeling sufficiently cowed & guilty, he will dangle the carrot of "when the debt is paid off" or "when my wife gets a boyfriend" - but he won't do anything about it.
If OP sees through his bullshit this time & pushes back because his words are meaningless & his actions tell her everything she needs to know, he will become nasty. He will browbeat her until she apologises for not loving him enough, or being the right kind of stepmum, for having her own feelings & wishes.
Keep having those conversations and encouraging him to find somewhere else.
This is not a man who responds to 'encouragement'.
He's already reneged on his agreement to pay down his debts & divorce his wife, as part of the moving in together agreement.
he believes he has Op right where he wants her - paying for his life while all he has to do is soft-soap but never actually deliver on his word.
When OP is ready to accept that she is going to be happier & freer without this man, she's going to have to do a lot more than "encourage" him to move out. He won't take well to having his comfy cocklodging disrupted.
OP - may I also offer you a personal & sincere apology for the, er - robust tone of my posts on your thread? I promise this comes from concern, not a desire to be mean to you. I have lived through a similar situation, & my friends were appalled & horrified for me. It took me FAR too many years to realise what a manipulative shit I had married.
The process of waking up to the difference between his pretty words (never delivered on) & his ugly actions was hurtful & personally diminishing. It is really, really hard to accept that the person you have poured so much love & concern into is actually just using you, & I am so glad that you are going to have time with your mum this weekend.
What you have with this man is a lot of FOG - Fear, Obligation, Guilt.
Used by narcissists & manipulators the world over to keep their partners/relatives in line. Please have a look at the link, & reflect on how much emphasis you have given on this thread to OTHER PEOPLE's feelings & other people's needs. This is YOUR thread, for you. Those kids, nice as they are, fond of them as you may be, are not going to be anywhere near as upset as you imagine they might be about their dad moving out & giving them access at a new place. They've only stayed at your place for what - a dozen times?
Why do you think it will devastate them that this arrangement changes? Who has been feeding this idea to you, & working on your over-developed sense of responsibility?
Look at some of the examples of FOG here - outofthefog.website/toolbox-1/2015/11/17/fog-fear-obligation-guilt
- & translate them to your own life
"I can only afford to pay 2/3 of the food bill, you need to take care of everything else"
"You aren't being a good enough step mother to my kids"
"I resent your attitude"
Can you see how much this plays on your sense of responsibility, & guilts you into offering more & more & more .... while he offers nothing, & won't even come good on the promises he's made about the divorce & debts?
Can you be really upfront with your mum about this, & listen when she sees how unfairly you have been treated? You desperately need an ally in real life: please see PP upthread who pointed out the cognitive dissonance you are experiencing. Your heart is listening to bullshit words, bullshit promises, & bullshit excuses, & wants to believe that this man is a good man. Your head, however, knows that he's bullshitting, because not one of his actions matches his words. This is why you are feeling in such a quandary - because you are waking up to an unpleasant reality, & part of you wants to shrink back & not acknowledge it. Talk it through with your lovely mum - SHE will have your best interests at heart. She can help you find a way to accept that this man is not the man he is selling himself as, & to rightfully grieve for the relationship you once thought this could be.