I’m not getting why the OP isn’t allowed to be angry and resentful?!
It’s a natural consequence of being in this limbo land of entwined lives but a strong desire to be emotionally disentangled.
It’s a motivating force, showing you that you aren’t able to sustain this current living arrangement. It’s a sign. It needs resolving by action.
Emotionally this current arrangement, is harming you. It’s draining and it’s keeping you tethered. It leaves you too close to this man who you used to be so invested in, and it leaves this open wall in your life and heart, where you’re exposed and effected by all his harmful poison. So, if you had a nice strong walk between you and him, it wouldn’t matter whether he was deluding himself that you’d change your mind. It wouldn’t effect you. But it does effect you now, as you’re wide open to him, he’s in your house, in the heart of your life and your mind.
What would happen if you did just ‘nip out’ when he was visiting one evening? To say he cannot he left alone with his two kids is a big fat statement... I want to unpick it a bit. Is this just one more negative way of behaving he’s fallen into, and you’re inadvertently supporting him in?
Take a step back, is he incapable or negligent in other parts of his life? Can he, for example, eat a sandwich in a cafe whilst talking to his boss? If he can then he can multitask and concentrate on two different things when he wants to!
I realize he is a revolting type of man who’s mummy still washes his pants for him, but if her, and you, are not around, what would happen to your dc? What are the real risks? Are they about temporary discomforts and upsetting but yes, not totally awful things?
Or are the risks of life threatening proportions? Or the type of neglect that would meet social services thresholds?
I’m really pushing this question as it framed what you can do next. And I’m not being unrealistic. Sadly, my boys father did not rise to the challenge of caring for his son. And I ended up letting stbxh visit our home to see ds, and managed to arrange either myself or a nanny to be there at all times. Obviously this couldn’t continue forever and it was awful living like that. Mind you, he was a hideously abusive and fucked up man, not just a bad husband, so I’m unsure how much he has in common with your ex-partner! Anyway, what I do think is relevant is that I couldn’t carry that situation on my back for too long before it was crushing me. He had the keys to our home, would arrive or not, as he pleased, and the limbo land that was intolerable to me, seemed quite acceptable and pleasant to him! The resentment, the anger, boiling and bubbling in me, ugh! I was working all the hours that God sent, all the housework, the childcare, I was exhausted, drained, everything revolved around me making sure ds still had a daddy... and it had to stop.
And it did. I gave him several firm but fair choices that worked for all of us, and included my own needs, not just sacrificing myself for ds need to have a father. It was ds fathers responsibility. Not mine. And not yours. All you can do is be reasonable, offer choices, maintain your own boundaries.
By all means think ahead and get plans in place for your future childcare needs.
My final observation, is that I’ve noticed that what I call ‘my’ needs are actually me and my little boys needs, as my life is all about my ds... but his father, well, his fathers needs are completely divergent from ds. I think that’s the same for many single or separating mothers. That thought might give you courage when daring to push for your ‘own’ needs.