GGB, I suggest rather than going for some smarmy anniversary card or note, that you take this post, clean it up a bit if necessary, print it out and give it to her.
Your wife (from your descriptions) doesn't come across as a hard case. Will it hurt her to hear your feelings? Sure, but it might just be the opportunity she needs to see just how impacted you are, how weary you are and she just might surprise you and step up to the plate for you. She may blow beforehand, but one thing I keep seeing is how we are so NOT honest with our spouses. She would probably have some hard things for you to hear, too.
But it might just be a chance to start the next 20 years with something more than despair.
