My wife won't take care of herself. How can I get her to care?

Start scheduling romantic walks with her. Buy a tandem bicycle for you both. Turn off the cable/satellite so she can't just sit around watching the tube all day. Stop buying her the junk and just buy the good for her foods. If it doesn't leave the store then it doesn't go down her gob. If she is the one grocery shopping, then turn off her credit card and do it yourself instead. Tell her you are concerned for her health and want to help her and you find that healthy relationship that you once shared. Let her know you are there to help her and to go through it with her but refuse to watch her kill herself slowly. My dad just had to go through this with my step mom of 27 years. She weighed 105 pounds when they met (and that was after 2 kids and they never had more) and she stopped having 16 years ago and now she weighs an amazing 350 pounds!!! She is finally working out with my dad and trying to make it work. He got to the same place you have and for that I am sorry. Talk to her. Ultimately, she has to want to change and if leaving her is what you have to do then do it because no one wants to sit idly by and watch someone they know, love and have shared so much with allow themselves to wither and die physically and spiritually.