What do you want from your wife? Do you want her to be happy? Is she happy? Is she happy being a Witness? Do you want her to be happy but doing what you want?
Let her be if you really love her let her do what makes HER happy not you.
Never mind what religion she is.
Marriages that fail have one or two very selfish people that want to change each other or just one of them.
Let her be unless you just want what YOU WANT.
People that become a JW usually have a need or problem give them that need solve there problem and they will drop the JW's like a ton of bricks. Maybe she like being with people that give rather than take?
And remember as much as you think you are right there is always that chance you could be wrong!