Ab, this man sounds so much like my ex it's scary.
I wish I had advice to give, because my ex was similar with our kids after we split. One DD at 16 had to have counselling, and her counsellor was a lovely guy, who after a few sessions wanted to meet me and her. Session went well, he saw how close we were, it was a positive and open session, with DDs needs at the centre. So far, so good. Next session, DD and her dad. DD came home in tears, said that her dad didn't want to engage, tried to turn all conversation around to him, and at one point the counsellor sat with his head in his hands. Ex wouldn't talk about DD.
Looking back, he wouldn't accept responsibility for breaking up the family home. He wouldn't face his anxious DD, because he would have to face himself, and damn well own the pain he'd caused her.
She had further counselling which helped her, she's fine now.
My ex too could see far more of his kids than he does. Our youngest was 13 when he left, and ex again wouldn't see his DS, because again I think he couldn't understand the utter bewilderment in his son's eyes. He felt rejected, because his dad had left, then rejected many times over, because his dad wouldn't put in the effort to see his own son, choosing to spend leisure time with his new partner's kids instead. Ex will never admit this, because his attitude has always been, "They know where I am, I'm here if they need me, but they need to make the effort.'
Men like this want to fast forward in their new lives. Partly to fully submerge themselves in their new found happiness, which they feel fully entitled to, and partly to minimise the pain those left, their kids in fact, feel. The pain is a mirror to their selfishness and entitled cruel behaviour, so they refuse to glance at it. It helps them then to say that their kids aren't making an effort. They forget the crucial thing though, they are the adult in all this. But taking on that role, manning up and owning their actions is a step too far. They simply lack the balls and integrity.
My adult kids see their father and it's ok. It will never be good, not because he left, but because he didn't acknowledge their pain, or bend over backwards to prioritise them, He just prioritised himself; and that was what caused us all heartbreak in the first place.
I just want you to know I understand. Your kids will be fine, you'll be fine.
It really is his loss, and when he acknowledges this, you all will be in a better place than him. x