David, I'm sorry to hear you're going through a rough patch. Like some of the other guys have said, if there's any way at all to work it out between you and your wife that leaves you both happy and intact as the people you are or want to be, then I'd suggest you work towards that goal first. If you have to be someone you're not, or she does, then it might be the time to go your own ways. My wife of 13 years and I split in 2001, it wasn't repairable by the time it finally blew up.
Now, I'm very happily remarried (go figure!) to a wonderful woman, who is the reason I'm living in God's country, knee deep in critters (horses and cats) and about as happy as an old guy can get. It worked out well for me in the end, though I still have regrets about my first marriage. You roll with the punches and re-build your life, hopefully having figured out what went wrong the first time around.
If you do need to sell, good luck with it.. I think the hardest part is accepting that it's not going to work, even after all the time and emotion that's been poured in to it over the years, and start over.
Like I started out saying, make it work if you possibly can, but not at the expense of being someone you're not. There's something said about "Be true unto thy own self".. sounds biblical to me and it probably is, truer words were never said.
Sean