What a audacious, gaslighting little cunt.
Ask him to have the children on a very rigid schedule, ideally he picks them up from school and drops them off and you can do that once a week and maybe he can do Fri pick up and Mon drop off eow?
I'm not sure how your logistics work but get something set in fucking stone, ASAP. Honestly I'd get a free hour with a solicitor over this.
You can't be forced to happily Co parent someone who's treated you like shit.
There's no end game for your relationship long term, he's fucked it.
He'll try coming back when his younger gf bores him or likewise.
It is hard to not engage with with a man you still love, but millions of us have had prolonged heartbreak from doing so, take it from us, your relationship with this bastard has died. If he comes crawling back its so you'll babysit his new baby when his soon to be ex wants her weekends out back. Its a tale as old as time.
Focus on you, break ups are shit but if you can Focus on finding yourself a bit through this, your goals, your free time, you use it to heal, use it to make plans, you're young, beautiful, you're going to have the hair and nails of dreams, nice hydrated skin and you're going to find yourself doing things that interest you.
Podcasts, books, make yourself some dating profiles and become tinderella when you're ready! Actually go on dates, you're not needing a husband, just have some good interesting stories behind you.
Never ever go back though, he's gone whilst you're young enough to be successful with a life without him, be grateful he's not fucked off when you're 70.
Remember, you're good things and deserve good things.
And please, this one is hard, but just to be careful, go get tested for any sexually transmitted infections, just so your piece of mind is sound 🌺