It's amazing that a guy with a "fiancee" and two kids gets to say whether the old ball and chain lives or dies.
More at Blogs for Terri.
Janette's doing some terrific posting on the subject, as well.
The ABA has a good tool kit so you can get an idea of the kind of input you can have with a living will and the Living Will Registry allows you to register the will/Advance Directive with your health care provider, local hospitals, etc.
However it is that you feel about these things, get it put in writing.