Take your time if you can. Read around this forum about others' experiences.
I still regret how did it.
First, I wanted to strengthen my faith by finding evidence to back up my faith. Result: 4 weeks later I non longer believed in God, the Bible, creation, and JW.
I hadn't told my wife about the investigation in order not to make her worried.....so when I was already very sure of my decision, I told her I would not go to meetings anymore.
She asked why, I tried to explain, she cried and got upset. I think it would have been better if I told her I cheated on her.
Some days later she was calmed down, asks why again, I tried to explain a bit. Cult defenses came up soon though.
We have written some letters back and forth in order to understand each other without the emotions of having a debate.
We're OKfor now, and have decided to not discuss religion for a while.
She hates it that I didn't bring her with me in my investigation.
I hate it too...she might have jumped ship with me if she studied what I studied.
My advice: don't tell your wife you made a decision or don't believe anymore. All her defenses may come up and then you have a problem.
Instead, tell her there are some topics you want to investigate together. Really investigate. At least then it's less of a surprise for her when you finally do show your belief is gone.
Also, I am with Hadriel: don't judge. You can believe whatever you want, and your wife has the same right. Don't argue about that.
And please remember, saving your marriage is more important now than getting your wife out of JW, or to agree with you.
Take your time. Good luck.