In reply to him using the kids as weapons, I would ask him nicely to please attend a coparenting class with you.

I'd ask in writing and save the reply. This is very ugly behavior that can damage the children a lot.

M 16 yrs, WH62, P54
3 adult blended kids
EA 11/13, BD1 6/14
PA fall 14, BD2 2/15
Piecing 2015, BD3 12/15
Separated 4/16
WH moved OW in 5/16
Divorced 6/15/17