Well atleast of the two of the parents you do your duty. You do care about your son as a person as he is. Your wife though well though she probably loves him has been misguided by religion to think that homosexuality is a disease.. something it isn't.
Some way religiosity is a disease...
Reality is that your son is 17 year old and for his own protection against a certain gone crazy person best is to ensure that certain gone crazy person can't force your son to go to "ex gay training"
This might cause a rift between you and here and that is the sad fact of what religion can do. Best is to protect your son.. sorry yo are forced this way but .. this is what religion does. Your wife needs time to get to grips with the situation.
Maybe it isn't all broken maybe you can show her that gay people in this age can have wonderfull relationships that last long. That they can adopt children so the grand children are no problem either. And that really she should look at the person.. not the sexuality.
So I actually feel she is panicked right now.. a tower of "truth" has fallen apart so to say. Religion must be for her a very strong supportive beam. And that her religion says her son is well.. nasty..bad.. it must hurt her allot.
Maybe I know.. it probably ends in a fight you can look into this issue. And see if you can't pry the religion away from the issue. You know like reminding her it is her son and that Jesus loved everyone. And the best way to do things.. is to love..
Many Christians are judgemental.. they are definitely not like Christ.
Good wishes in a troubled time. May these possible methods aid you. If all goes well this situation doesn't destroys the family. She might just need time to adjust! I am very happy you are so supportive of your son.