I don’t think you can separate fatherhood from family, or how a man treats his wife.
Gay or not, he abandoned her for another person. That is something he did TO the OP. That is harsh, that is cruel. I’m not sure what the right answer is, but this is how he treated THEIR MOTHER. He is continuing his cruelty by breaking even more promises, and not continuing to support her raising them in the Catholic faith, but inserting another faith in the mix.
While he goes on merrily with his new wealthy spouse, she is left impoverished. Let that sink in. She likely cared for his children at the expense of her own career development, and he left her impoverished for a wealthier spouse. As far as the children go, he will then hold cards for their affection, in him being able to provide for them in a way she cannot. If my dad had left my mom for anyone, but in particular a wealtheir person, and left her impoverished while he was living the good life, I don’t think I could think positively of him.
“good” fathers do not act like this. A good father would understand his children’s affection for their mother, and not put her in this terrible situation. He had a chance to throw her a bone - raising the kids Catholic, and he couldn’t even do that for her. He had to take it all.
Yes, it is likely better he remains in their lives, and contributes to their upbringing. But in no way should the OP’s pain at abandonment of her marriage vows and her family life be construed as “bitter and manipulative”. The best he can say is “I treated your mother horribly, I am sorry, and I ask for forgiveness, both yours and hers”. Then, he could say “You are being raised in the Catholic faith, because this was a promise I made, although I no longer believe, particularity the church’s stance against gay marriage, I thought I could at least do this for your mom, since it was so important to her” .The problem is he does not seem to be acting even a little sorry.
Of course, she can try to heal by “moving on”, but that is much harder with the financial situation he has left her in. Her recovery will not look like his. And remember, he has gained the life style he wants, and she is trying to rebuild what was lost. There is a difference.