Second... on the kid front. They have to develop their own relationship with their mother. Your son shared what his mom said, turning to you for understanding. You are safe. You are home. You are Dad. You aren't going anywhere. You love them. You are a caring mature adult.
This is the time you share what fits within the 'big picture' of their lives, perhaps giving a perspective of why Mommy feels that way, how you feel, how you care for their well being.
This isn't the time to rescue her, to call and give her advice on how to be a mom, parent, adult. This is her path to learn and feel. You're the foundation for your children but it's not your job to tell her how to be with her kids. Even when married, parents approach parenting differently.
You take care of the kids on your time. Keep your boundaries. Respect hers. Let her ask for help. Learn how to not automatically fix. This isn't about you, wanting to control the complete wellbeing of your children. It's not fair because anything you say will work against you.
Look up the effects of an emotional triangle. Keep your communication as a direct line.
