I also keep my finances separate from my DH for similar reasons.
My DH has worked for Home Depot for the better part of the year, and only brings in $9.50/hr part time. He pays his half of the bills, and for any extra goodies he needs. He constantly feels broke - because he is - and it's that pressure that has pushed him to find another, and better job. However, it's taken a couple of years of therapy and spotty joblessness or underemployment to help him tackle the obstacles holding him back in that hugely destructive Anxiety Zone.
In this situation, since it's your DW, it's up to you how much of an intervention you want to stage. However, if something doesn't change, it looks like you guys might be on the rocky road to divorce - not recommended unless it's really the only option.
Does your DW see a psychologist? If not, is she willing to? Chances are, if she had a breakdown due to an anxiety disorder, she may not have fully recovered. Have you considered trying to seek out a psychologist that not only works with anxiety and mood disorders, but also is a financial psychologist?
http://www.financialtherapyassociation.org/FTA_Network.htmlCan you, or are you willing to take and destroy her credit cards? That's pretty dire, but not any different than staging and intervention on an alcoholic or a drug addict. Waiting it out while she heals is only going to be bearable as long as you feel the hole isn't being dug any deeper (or, that's how it's been in my situation,), but even if you destroy all her ability to spend more than she makes, she may very well still continue to try to get more credit. Although, after her credit score tanks due to past due bills... You get the idea.
From your story, it's true that you're the only one able to plan and work toward financial wellness, but it certainly sounds like your DW has bigger wellness fish to fry than financial ones. Having patience while she does this is going to be a struggle (from experience!). I got my DH to go to therapy by going myself, and sharing the experience with him if he wanted to hear about it. After about a year, he decided to start going as well. I still go, for some PTSD, but mostly for guidance on how to be patient with DH while he heals emotionally from his own abusive experiences. This year he paid off all his debt and kept a permenent job, and next year he'll be starting a new job making more money and learning more about how to manage himself.
If the DW isn't willing to look her demons in the face, though, and isn't willing to replace the obsessive spending bandaid with therapy tools and proper healing... I don't know what other advice to give, other than to take the money - and the kiddo - and run...