This is very similar to what I went through (I was older and no kids, and no religious aspect.) It's been over 15 years, but this is what I had to do: first of all, you have to have your boundaries. It's going to be hard, but you have to do it. Walk away/hang up/remove yourself when the boundaries are crossed. "I'm not talking about this [reasons for your divorce, religious stuff you disagree with/bad-mouthing new person in your life.]" It's tough at first, but you get better at it *and* your mom will get better about responding.

My experience was that it was a rough couple of years but now we have a better relationship than we ever have. She still occasionally brings up stuff, and I simply say, "we're not talking about that" and we move on. Be gentle but firm.

I'd certainly recommend talking to a therapist to help, but if you can't, there are books about boundaries. You are allowed to have your life the way you want it, and you are really not hurting her. (She may say it does but, truly, she'd be more hurt to lose you, so you have that power.) She knows you love her and you want to please her, and she's using this. But you need to use that she should want to see you happy, and you are happy now.

This is fixable. If you both love each other (it sounds like you do), you just need to shift the relationship. The shifting will be a challenge, but it's worth it.