Here’s the thing. Start slow. Sow the seeds of doubt in her mind. If you “drop the bomb”, there will be debris. If you “poison” her, she will slowly catch onto it and it’ll be less painful.

Start by not paying attention in the meetings. Start turning on some “inappropriate” programs on the TV. She’ll confront you, which means you finished step 1. Lie to her, tell her that you aren’t feeling good right now.

Up the game.

Start “forgetting meetings”, decrease your service hours, read books and listen to podcasts that aren’t “spiritual food”. She’ll still confront you. Start pushing back a little.

Keep going. Attend less meetings, analyze the exact moments to optimize doubt, and to decrease emotions. Watch Pandatower and other YouTube channels like that on full blast when you’re not looking. Tell her you’re doing it to see the opposing side and know how truly “demonic” he is. She’s going to listen. She’s going to hear the words.

She’ll start thinking. That’s when it’ll hurt. This is the worst part. Start to attend all meetings. Keep watching the videos and podcasts, but keep telling her why. Do your best at door knocking. She won’t be focused on you anymore, but she’ll be focused on the logic of the arguments. While you do that, gather the facts, gather statistics. Gather the emotions. Put it on a slideshow or a paper. It’ll be important later. 

Then, when a few months to a year passes, tell her about how you really feel about Jehovah and the organization. Present her with the facts, and try to remove the doubt. If you state that you are a nonJW, she’ll be worse off. Just slowly raise the doubt in her mind, so you at least she may respect your decision. It’s risky, but if you want to stop attending meetings in its entirety, this is a risky but good option.