Difficult and Uncooperative ex!

[WeeMcBeastie]

Long story and just need to have a rant as my RL friends and family are probably fed up of listening.
I divorced my ex last year after 18 years of marriage, we have 2 children, 18 and 16. He was emotionally abusive, he cheated and was a general arsehole (that would be a whole other post!)
He was surprisingly more cooperative than expected during the divorce process but probably because I found evidence that he'd cheated and he was afraid of any repercussions for his OW. However, since then he has been extremely difficult and awkward with myself and my daughters. He refuses to respond to texts or phone calls and on the rare occasions he does respond, he's very hostile and antagonistic. He has joined what I can only describe as a religious cult (he was previously an athiest who would actually go up to religious street preachers and ridicule their beliefs!) and as a result he refused to acknowledge oldest daughter's 18th birthday. This has really upset her. We agreed to split the costs of an activity she is doing but he is now being awkward about paying his share. After screaming and shouting down the phone at me earlier in the week, he then text me asked me to text him to explain another issue to him. This was 4 days ago and he hasn't responded despite it being quite urgent and him going away on holiday next week, I refuse to play his games and won't text him first. It's as if he really doesn't care about his daughters at all. I have tried speaking to him several times to suggest that it's better for everyone if we can keep things amicable but he doesn't seem to be able to maintain this for more than a few weeks. I couldn't care less how he treats me but I hate to see my daughters suffering. He's a difficult person generally, he doesn't have a single friend who has been in his life for more than 2 years and he has fallen out with most of his family (always their fault and never his!) Does anyone have any experience of how to deal with this or do I just have to accept that he's a twat and it's always going to be like this? Roll on 18 months when both daughters are at uni and I no longer need to have any contact with him!