JG that's a very good start. I think (it's been a while) this is the first point that I admitted to myself.
I was raised for years to ignore the 1914 and 1975 false predictions (didn't even know about all the other dates). The automatic response was "but Jesus' apostles had wrong ideas..." However, you just can't get around what the Bible very clearly says about false prophets.
If ANY other group on earth said the end was going to come in a particular year and it didn't, JWs would see it as sure proof that they were false prophets.
Don't expect your wife to just accept this argument; there is probably too much conditioning to overcome with mere logic. But if she was being honest with you, it should be enough for her to at least consider other points.