As to the memorial, the only important thing to remember is NOT TO drink the wine or eat the bread. It's a major faux pas, as this is a privilege for only a few people who believe they are in a special group of 144,000 people who will go to heaven. Everybody else will live the earth, so they are supposed to simply pass the wine and bread around while not drinking it. It's their only real celebration all year, so people tend to get dressed up a bit more, but other than that it's as boring as the other meetings. It opens with a prayer and song, there is a talk, which emphasizes that you SHOULD NOT drink the wine or eat the bread. Then there is a prayer over the wine, then it gets passed around so most can refuse it. Everyone tries to see if anyone actually does drink the wine, so they can gossip about them and speculate on their mental health. This is because the religion taught for years that the number of the 144,000 were all ready picked, but they keep getting more partakers so after various other explanations, they started hinting that those people have mental issues. The same thing happens with the bread, then another song and prayer and the ritual refusal to celebrate the sacrifice of Jesus is over.
I think you should go, as it's an insight into how irrational the religion is, but do go to a regular meeting as well, it will help you better understand why your wife is the way she is.