Hello and welcome! Sorry for not replying earlier - it’s been one of those days
You sound really in the thick of it - 5 kids with different ex’s!
One thing though - nothing is your fault. You met a man with kids - you have relationships to manage but so does he and should work with you on things. How are your kids getting along with his?
You say fiancé - so is there a wedding in the offing?!
Do his kids have regular schedules of time with you two so you can work out routines?
I’m sure others will come along soon - you’re not alone in this kind of situation. One word you’ll probably hear people mention is - detach.
It’s a kind of way of letting it all go over you and detaching from it all and finding that moment of space where you remember who you are and feel grounded.
It’s also about putting certain people out of mind and focusing on your own life and home and relationships and not letting the ex (or exes) get into your head.