I feel for you. But yes, that's kind of the extended story of my life too. Except you still have a way out.
I admire your straighforwardness with him. But apparently his mind is closed to simply accepting new info at face value. His mind is clearly devoted to the "provisions of the Faithful, Discreet Slave". So simply handing him new info you got from "lying apostates" probably won't do much good, as you are discovering. At a stage such as this, the strategy is to open his mind to get him to think. Ask simple questions that you can't quite resolve yourself, and present it to him that way. Approach him with a curious, questioning and concerned attitude. Here are some good questions from freeminds.org (which you may have seen already). Now, it's not necessary to cover all these questions. Just pick out some that strike a chord with you and genuinely ask him now and again and discuss it. It's a whole lot more convincing when you do it this way than when you seem to be memorizing questions from a script. Don't approach it with the attitude that you want to make him see things your way at all costs, but show him you are genuinely curious about the truth. Then you can point out specific things the WTS has said with regard to your questions. As he seems to be willing to check out some of what you've read on the internet, perhaps you can direct him to http://quotes.watchtower.ca where one can verify the WTS's own stated position (past & present) on key matters. That is if he'll look at it. If not, perhaps you can print out hard copies of actual WTS scanned publications available on the net. Here are more ideas of types questions to ask from a Biblical perspective: http://www.biblicalanswers.net/wit2others.html
Oh, one other thing: it's far better to pick out and concentrate on a couple of good issues and go over them in detail than to try and use the "shotgun approach" and try and show him everything at once.
The thing is getting him to see that perhaps there is a difference between seeking Jehovah, and having to become totally loyal to an organization with its whole set of policies laid out as the means of accessing Jehovah and earning salvation.
As for where to go to in the Bible, I think anywhere that emphasizes coming to Christ for salvation, like Romans, Galatians, John, 1 John, etc. would be good.
All this sounds pretty daunting, and to an extent, it is. But just take it all in, concentrate on a couple of key issues, and see how he responds. If he seems to be unwilling to reason, then I would sadly say that you ought to move on...