J.J.
Wow M., I'm sorry to hear that you are unhappy. I have been w my husband for 17 yrs already and we have had our ups & downs. I have felt the same way you feel, the "don't touch me, you make me sick syndrome" (& he never got it) and believe me I have left him before & came back to try to make it work (esp because my kids were so young), I thought it (life & him) would change & not until the last break up did I see a dramatic change. We needed some time apart...to miss eachother.
So I understand how you feel. Sometimes, it just isn't there anymore.
First, I want to say see if you can make it work...try, do something that may bring that spark back up, like maybe a small vacation with just the 2 of you just to reminisce on the GOOD stuff.
Or perhaps, YOU need a break, some ME time, and do a temporary separation first, to see if that will really make you happier.
Then if that still doesn't work or you just know you want to be completely out of the relationship... my advice is to cover your every move before you leave...meaning prepare carefully, do not do it haphazardly, leaving some stones unturned. Take care of your paperwork, separate what is yours, start setting aside your own accounts & money, start packing here & there and store them in a storage facility, get you a PO Box and start transfering your mail so that eventually, when you make a move, the postman already knows to forward your mail. Plan ahead. You didn't really mention what his temperament would be, but CYA anyway.
I hope things work out for the better for you as well as the children & I pray you all have a happy life (with or without him). Take care & keep your head up!