it has been rushed on his part not mine because he was so keen to give his children the family he couldn't with his ex
Wow. There's a lot to analyse just in that sentence alone - it manages to:
-
Sound like a compliment - "You will give my kids a better home than their own mother" - but is in fact encouraging you to feel in competition with his ex
-
Absolve him of parenting duties - there's no way he could be his children's family ON HIS OWN. You have to be there and do it for him - sorry, I mean "with him".
-
Load responsibility for creating a family onto you and your kids - "my children deserve a family, so you and your children must accommodate them".
-
Pressure you into remaining in the relationship - if you choose to end it (which you absolutely should, you sound miserable btw) then you will be taking his kids' FAMILY away from them.
I'm sure that you love his kids - that's what a certain type of man relies on. He has banked on you caring about his children, and therefore finding it harder to leave the relationship. He also had no intention of doing the day-to-day grunt work of actual parenting - he got a woman (you) in as fast as he could to make sure that packed lunches were made and gym kits washed and appointments remembered and disputes refereed, or as he would put it "My children get the home they deserve".
I'm sure he talks a lot of guff about how it's better for the kids to have another adult there to love them, witness a loving, stable partnership, blah blah, how you make him a better parent, how you're all a big happy family, but the truth is you are there to make HIS life easier.
And your kids may be attached to him, but that is no reason to stay - people often misunderstand the way children become attached to the caregivers in their life.
Basically, young children are very vulnerable, and their best (and only) chance of survival is to make the adults around them fond of them and hence prepared to take care of them. So children are wired to bond incredibly quickly to adults because they have literally no other way of trying to keep themselves safe.
Don't think that just because your children appear to like your current partner that they are somehow correct in their assessment of his character and you must be wrong. They would have bonded to pretty much anyone that you moved into their home and told them was in charge.