For me, I had to ask myself two questions before I made the decision to leave an alcoholic husband:
1. Can I tolerate living the way things are now for the next ten-twenty years?
2. Have I done everything that I can to change the situation (bearing in mind that my ability to change things is very limited - I can't change other people)?
When the answer to 1 was clearly "no" and the answer to 2 was clearly "yes", I knew I had to go.
Only you know whether you are in the same boat. However, it sounds like your wife's condition is not improving and that you will not be able to realize some of your life goals, like having children, if she continues to deteriorate.
You mentioned feeling guilt about "dropping" her. I think there's a difference between "dropping" someone and making the decision to let them go on their own way.