Nooo!!
Sorry OP, but you’re not thinking straight and what’s best for your joint kids is a parent who can afford to live in a decent home, pay the bills and be there for drop off, pick ups and the long school holidays!!
Your ex has happily not been inconvenienced by childcare responsibilities for the last 10 yrs because he’s had you to do all that for him and he’s clearly taken you for granted and is still trying to convince you that childcare is 100% your responsibility as The Woman.
If he’d stayed at home instead of you, you could have progressed your career and you’d be earning a higher income and not worrying about how to manage the childcare as you’d easily be able afford ‘paid help’ to deal with the non school hours.
You’ve also sacrificed your ability to save into a pension scheme too. My DH’s pension is about 5 times what mine is because he carried on earning throughout the child rearing years. I’d be completely stuffed if we split up now.
You need to leave with more than 50% equity of the house if this split is going to be remotely ‘fair’ to both parties and yes, not getting married was clearly a mistake on your part, so don’t compound that by thinking taking more than 50% equity is fleecing him. He’s had a free ride for 10 years!!!!!
My DS also has SEN and can only be left alone for about 3-4 hours now he’s 16. Not a chance would I have done that when he was 11.