There's a sort of unknowable Zen to it, which is why I screwed up my courage to ask if anyone had real, practical advice for that thing that has to happen in your brain.
I achieved my tranquil Zen state of what others call detachment as soon as I got so pissed off with myself and my wife that I didn't want to be around myself or her anymore. I was upset with myself because I'd been a feckless doormat and I was upset with my wife because she'd been wiping her dirty stinky feet all over me.
My wife had planned to move out at the end of the school year. After I achieved my Zen-like state of tranquil pissed-offedness I asked her to move out a few weeks early. After she moved out, over the course of a few days, I realized that happiness was in abundant supply and I knew that I never cared to be in wacky-world again. And that was that. I think the experience may have been a bit different for others.
Do I love my wife? Yes, of course I love her, but the oft quoted quote "you didn't break her, you can't fix her" applies. I have two sons to look after and I have to continue living my life. I chose to enjoy myself which, in part, seems to include building things with cedar and planting lots of plants. Who'da thunk?
By the way, detachment is something everyone talks about, but never actually accomplishes. I recommend a state of tranquil Zen-like piss-offedness.