CB what is ordered in the court order re contact? ie is the skye contact ordered?
Your primary role as a parent is to protect your dc (yes even from their parents if necessary) and you can break the court order if you feel you have sufficient grounds too and your sc are being subject to emotional harm.
Have you considered phoning your CAFCASS officer and saying that you are concerned to the point of thinking contact should stop.
If he is serious about being a parent to his children he will go to a parenting course if the alternative is not seeing them.
Definitely chase up the co-parenting session for you both. Go along to yours even if he doesn't go to his.
Send the book along, he can choose not to read it but I bet he has a look even if he throws it back at you too. Just keep sending it.
Start keeping a diary of things, events, dates/time and what was said by who to who and how your dc reacted.
And please don't ignore things he says about you completely. You will look like a dormat to your dd and if you don't answer any questions she might have then she might start to think they are true.
If you continue to let these things go then your dd might start to believe them and it could even lead to PAS against you in teh future.
en.wikipedia.org/wiki/Parental_alienation_syndrome
You don't have to criticise her dad but you can respond with comments like We all say hurtful things when we are upset, or I don't know why Dad would say such things, or It wasn't up to dad or me who you should live with, we felt differently on it so we had to ask the court to decided who you should live with and this is what they decided for us.
At the very least you should speak to your CAFCASS officer/solictor to ask what is happening about the parenting course. I think you also need to consider a letter stating that unless this behaviour stops you will have no option but to stop all contact or limit it to a contact centre only.
Ranting is fine, but you need to take some action now to resolve these issues if you can. Not easy with someone who isn't willing or ready to see their actions are hurting the children.