You'll have to surrender to this whilst he has them 3 nights a week.
Talk to his teachers, principal, doctors, everyone BUT him and should they agree with you they will raise it with him.
Do not try to reason with him - he is well beyond that. Do what you can legally and via CPS and try to let go of the rest.
I was in a bad place about his shit parenting a few months ago and it was killing me.
SI came to my rescue and reminded me that I'm not responsible for the kind of father he is. I can't control what he does and raging against it was just making me crazy.
Now I expect less than zero from him. I am not surprised or disappointed. I'm prepared for it. I move my body with the wildly rocking boat rather than try to stop it rocking.
His fuckery can still make me hopping mad sometimes but it doesn't consume me like it once did. Now I just feel sad for my girls - they deserve so much better. I hope he does better for them but I won't hold my breath.
When he lets the girls down I am there for them without taking on any of the burden of responsibility. They know he's the one who let them down. They know its not because of them but him. They know they can talk to me about it and I encourage them to raise it with him.
Detachment was easier as a wife than as a mother co-parenting with an incompetent imbecile. But it's essential.
Expect zero - fight what you can via lawyers/CPS, be their loving/stable soft place to land and surrender to the rest.
Their father is a fuckwit - it might be a permanent condition. You can't control what he does/doesn't do but you can control how much you let it impact you. Pick your battles and practice allowing the rest to roll off your back. Don't fix his mistakes as that would be a full-time job. Just hold your end - if he can't hold his end he might just have to give them back.
ETA getting into it with him to try to change him just adds fuel to the fire. Total NC, he doesn't exist. It works for me.
[This message edited by StrongButBroken at 2:54 AM, April 10th (Wednesday)]