Realistically, he is being the smart one right now. The best thing he can do is shut up and watch from a safe distance while she self-destructs.
While I agree that she may be suffering from PPD and other effects from childhood, she KNOWS the custody battle is looming. I've seen people in the throes of depression get help only when their children are on the line - it is then that they will finally seek treatment. Brittney doesn't seem to care.
While I feel for her and whatever she is suffering through, the time comes when you have to grow up and be a parent. If she loses custody, it will be because she forfeited it. I feel more sorry for those children, who seem to have already lost a mother. Anyone that disturbed, drunk or hungover is unable to be fully present for their children.