The stages of MLC are just a guideline and timeline for the emotionally turmoil that crisis people are in. Each person is unique, therefore, their crisis will be unique because of their personalities and childhood experiences. My personal opinion is that your wife has slowly been entering into crisis mode and she's still waffling about staying versus leaving. From your posting, I do not see much in the way of replay. As the stages are linear, they can bounce back and forth from anger to withdrawal and back again. Depression is the main ingredient of MLC and when she does hit the really dark depression, she will withdraw from everyone and everything that she held near and dear. She's not done that thus far. When they have a crisis, it is because they weren't allowed to go through the normal "growing periods", i.e., 20, 30, 40, etc. We each go through this and if not allowed, well...a larger crisis will take place down the road. Also, MLC is about revisiting the past, a past that will take them back to the time where they were emotionally stunted. This can happen when an authority figure does not show them admiration or recognize them for what they've accomplished or who they are. It could stem from abuse of any kind...but they have to go back to that time, revisit it and face their demons before they can begin to grow up and heal from those things.
So, what do you do? Give her plenty of space and no pressure. Do not pursue. No expectations as the woman you are dealing w/is now the exact opposite of the woman you use to know, i.e., mirror image. Has the spending by her ramped up? If not, it very well may...so watch your bank and credit card accounts. As for her spiraling out of control...if she is in crisis, she will do it no matter if you are there or not. There is nothing you can do to stop it once it begins. If you attempt to snap her out of it, she may come back to reality for a bit, but eventually she will enter it again and that time will be far worse.
I would suggest that you attempt to keep the focus on you and your children. Find things to keep yourself busy and just give your wife the time and space she needs. She may not show it, but she does feel guilty and ashamed for what she's doing...but it is something that she has to go through in order to grow up.
As for counselors recognizing MLC, many of them are aware of "changes in one's personality", but MLC is not a recognized disorder by the medical society.
As for showing affection to her...follow her lead. Actions always speak louder than words.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.