Does your wife understand why you don't want to go? Do you understand why you don't want to go?
It may not be easy, but you're gonna have to tell her the things that have caused you to question the religion. Is it faulty doctrine/prophesy? Is the JW lifestyle too restrictive? Is it just plain boring and dumb? You need to be able to thoughtfully, tactfully and slowly explain the whys and hows to her. She'll probably still get defensive about the "truth" and claim that you're just not "thankful for what Jehovah has provided...blah...blah...blah", but you have to be able to intelligently defend your position and what you know is true. To just keep quiet and hope she doesn't "make" you go is not fair to anyone.
It's hard, I know. I've been there, I'm still there. I get the guilt trips, the speeches, etc. She just hasn't opened her mind up enough to see what's going on, but I hope one day that the right trigger will open the flood gates and she'll see what I was trying to tell her all along.
On the flip side, what's so bad about an occasional meeting or convention? Granted, I could never step foot in a JW meeting of any kind and be perfectly happy for the rest of my life, but at the same time, I refuse to run scared. If the occasion comes up where my presence is required for whatever reason to go to a KH(remembering that I have lots of family still in) I'll go. I'll go with my head held high and be friendly and nice to all that are that way to me. I'll use it as a social occasion to visit old friends and then zone out during the religious part of it. Conventions are a waste of time but if it keeps peace in the family, it's sometime better to go. But it's great to wander around during the sessions, glaring at the little MSs with their "please be seated" signs. Checking out the hotties is a good way to spend the song and prayer time. Everybody else is busy, so it's easy to let your eyes wander around and not get caught by the missus. Hell, If your brave enough, take a book to read. I recommend "The DaVinci Code".