I do NOT agree that your wife is one who NEEDS a divorce in order to straighten herself out.
From what you've shared, your wife is like a fart in the wind. She bounces from one emotional state to another. My guess is that a divorce from her will not change much in how she interacts with you. The two of you have had WAY too long to establish the dependency relationship you both have with one another.
I'm thinking divorce for your wife is very much like a fries or cole slaw decision.
Bill
"Don't tell me the sky is the limit when there are footprints on the moon."