It is interesting to say you stop thinking straight. When a person's blood pressure rises through anger or fear they actually start to loose control. This is a problem for police, as in times of intense situations they start to react without thinking, leading to shooting innocent people. The way to get around this is to not speak to your uncle about these things once you feel yourself being worked up.
I would recommend maybe writing to your uncle instead. It is unlikely to open the closed mind, but at least you will feel you had a say and will find it easier to move on. For example, I would write that you do not wish to discuss anything to do with the WTS as it upsets you to see him selectively forgetting the inconvenient truth about the Watchtower teachings and ignoring reality. For instance, regarding the conversation the other day he made the following points, each of which are wrong. You will never have anything to do with such an inaccurate and manipulative organization so any further conversations regarding it are pointless (or something to that affect).
Generation.
"If you are a young person, you also need to face the fact that you will never grow old in this present system of things. Why not? Because all the evidence in fulfillment of Bible prophecy indicates that this corrupt system is due to end in a few years. Of the generation that observed the beginning of the "last days" in 1914, Jesus foretold: "This generation will by no means pass away until all these things occur." - Awake!1969 May 22 p.15 - Click here for scan
Likewise today, most of the generation of 1914 has passed away. However, there are still millions on earth who were born in that year or prior to it. And although their numbers are dwindling, Jesus' words will come true, "this generation will certainly not pass away until all these things have happened." This is yet another reason for believing that Jehovah's thieflike day is imminent." Watchtower 1988 April 8 p.14
Blood
Fractions not Allowed
- "If you have reason to believe that a certain product contains blood or a blood fraction…if the label says that certain tablets contain hemoglobin…this is from blood...a Christian knows, without asking, that he should avoid such a preparation. Watchtower 1961 November 1 p.669
- Fractions Allowed
- "...when it comes to fractions of any of the primary components, each Christian, after careful and prayerful meditation, must conscientiously decide for himself." Watchtower 2000 June 15 pp.29-31
- Tetragrammaton
- The tetragrammaton has never been found in any ancient New Testament manuscript. If the apostles weren't using it then it is irrelevant today and not important to be used. See http://www.jwfacts.com/index_files/Jehovah.htm