All through our M, my W has been the financial keeper. She is extremely good at it and I would take her back just for that reason (just kidding!). Having said that, I wanted to grow up and take ownership of my finances right after she walked away. We separated our finances amicably. This was part of my 180 at the beginning of my sitch so that I could show her that I can take control of the finances. I felt insecure at the beginning, but I feel much better today about splitting our finances right away with a MLC WAW. I am still collecting and putting together the pieces of the financial puzzle; this is not my forte, but I defintely feel better about myself.
You have to decide whats best for your situation. I know you have to give her space and show your friendly side, but its better to set the boundaries early than later, I believe.