I would focus on you and your son. Any interractions w/her will be an example of the changes you have made (that you considered needed to be made).
I would lead by example.
I would implement some solid guidelines for scheduling of son visitation/flexibility.
I would be pleasant, but only engage in conversations regarding son.
I would cut off her ability to use you as an interim "fix" for conversation/emotional intimacy.
I would absolutely make sure you are protected financially. (debt)
Lastly, I would move on.
She may come back w/real remorse one day... But, Starsky said it best... This isn't a quick fix. You needs to see their changes for more than months... Possibly over a year. Words match actions.
If she doesn't come back w/real remorse, you've already begun a solid foundation for you and son.
Stop feeding her.
Me-46, D-21, S15, S13
After many years w/my head in the sand... I FILED Divorced 6/2011
The average woman would rather have beauty than brains, because the average man can see better than he can think.