Welcome, toweragent. It sounds like a formerly firm foundation has all turned to mud, and you are floundering. I suggest you take your time firming up your beliefs this time. It is during this time of uncertainty that you will do your deepest thinking, and it is this exercise I believe that is best for you. Don't take answers given here as gospel, either.
"How can I be SURE that the Watchtower organization is NOT being used by Jehovah? How can I be sure that they just haven't gone astray like the apostate nation of Israel? "I will make Israel an object of mockery and ridicule among the nations." I Kings 9:7: It certainly seems as if Jehovah is letting the Watchtower get mocked, and rightfully so. But will they ever be acceptable to him?"
Might I suggest that the cycle of revelation, establishment, coasting, fail, and renewal is common to all people, all nations, for all time? Why should Isreal have failed so badly that Jehovah would not forgive? While WTS was forming up, Isreal itself was rebirthed as a nation.That doesn't sound like Isreal is condemned for all time.
WTS's failure should not be used as "evidence" that they have the truth. Otherwise you also have to consider if Bozo the Clown is the resurrected Messiah.
I judge every organization by it's fruit. This is also biblical. Bad fruit, cut it off. If the tree holds on to the bad fruit, don't trust the tree. I trust the Red Cross. Not for spiritual matters, surely, but it is a proven reliable organization.
I suggest when you attend meetings, take more notes than you ever have. Mark down weasel words. If they use the word "evidently", have they truly provided the evidence? Make note of your questions and challenges in your notebook. If a verse is quoted, did they provide it in context? Did they use a bible verse at all? Did they leave anything out that might be critical to their position? Once you start looking, you will find flawed thinking and sloppy verse use everywhere.
I suggest you don't bring up doubts or tough doctrinal topics with your wife until you are more settled in your mind. There is an exercise you can do now though that helps every time. I know, because I am married to a Witness. There is in every person a core of their natural personality, that is separate and apart from the put-on Witnessisms. You recognize the Witness. They give the same canned greetings, dress the same, smile the same.
I am talking about something else; those things about your wife that make her unique and special. What are her talents, hopes, and dreams? Did she set anything aside to be a better publisher/pioneer? Might she like to take it up again? Do all you can to enhance your natural woman. She comes out when you are away from the meetings and literature the longest. She shows up on holidays, in jokes and laughter. Learn to spot the difference. You will only ever talk heart-to-heart with this natural woman. Ask her what she thinks, how she feels. Even if she is still a staunch supporter, respect her for making up her own mind. It is the awakening of this natural personality that is critical to independent thinking.