For your own health and well-being, you need to stop going to the meetings. Let her go alone.
She'll try to guilt you at first. But I bet she eventually starts justifying staying home herself.
I'm going to be blunt here.
JW's justify staying in the organization by saying that even though there are problems, it's the closest thing to the truth. They're afraid of God (a fantasy), afraid of not seeing loved ones again (another fantasy). If you still believe in God, you're feeding her fantasy and her hope, and she'll never let go. She might become weak and somewhat inactive, but I doubt she'll ever completely leave the cult and will likely feel guilty the rest of her life if she does become inactive.
If you wanna believe in God, fine. But realize that if you believe in that big bully in the sky, the organization has a lot of emotional leverage over you and your loved ones.