Based on my wife's cousin's advice, I took our son over to her uncle's house, dropped him off with her, and then took her credit cards. He had had a very long conversation with her and told me that she thinks she can do whatever she wants and I will watch our son and finance her. He felt that I should shake her out of her fog and back into reality by showing her that if we get divorced, it's gonna be hard, she will have to take care of our son, she won't have my money (she's never had a job before) and she won't have my car. It was hard but it did feel right.
She was furious, but I didn't engage and just went home and went to bed.
Don't worry about our son, she is a good mom, she is just being selfish right now.
