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You and your wife seem to deserve each other, and I can see that having you together keeps a lot of other healthy people from accidentally hooking up with either of you. But what kind of example are you setting for your child? Do you think she isn't beginning to catch on to Mommy's 'shopping trips' and phone calls?
Get a different therapist, or a spine transplant, and create the kind of life that will be a good example to your daughter. Divorced and healthy beats married and crazy, unless you both buy into the craziness. Your wife will never change because she doesn't think she's doing anything wrong. You realize now this isn't working, so now you really have no choice but to deal with it. The veils that gave the illusion of beauty and mystery have fallen to the floor, revealing the sick and tawdry situation you have accepted for too long. You can pick up the veils, but you'll aways remember what you've seen -- and that changes everything.
Good luck.