I'm afraid that my uncle will shun my gay cousin if he brings his boyfriend to my Christmas family reunion?

My cousin Ryan is gay and my uncle Daniel has had hatred towards him since a family gathering on Memorial Day 2007 when he ignored him when Ryan asked him if he could have some potato salad and then said to him “Only straight people can eat potato salad, you and other the f-ing f*gs in this planet should eat potato salad when it goes bad!” in front my child, my nephews, and nieces all who were around the ages of 7 months to 11 years old (at the time). My aunt Megan and my other uncle Benjamin (his parents) are okay with his ually and are really hurt whenever Daniel calls or visits them from time to time to usually criticize their parenting skills on “Why do you still keep talking to that f*g that is your son, just disown him!!!” because of what he did that May 2007 day and several other incidents after that, he was not invited to my family’s biennial Christmas family reunion (Megan and Ben were the ones that hosted this in Christmas 2007) and this year my wife and I are the ones hosting this and my wife told me to invite my uncle because his granddaughter (born May 2008) will be upset not to see her grandpa and is inseperable from him and my cousin also has been thinking about bringing his boyfriend of 11 months as well to my Christmas family reunion. I keep having nightmares that it’s Christmas morning and my uncle refuses to give my cousin anything and brings throwing his Christmas presents at him and tells him to go in the pantry with his boyfriend and have them open their gifts up there away from the family. What should I do?? should I ign seating arrangements for the Christmas dinner, have my aunt Ashley (Daniel’s wife) keep an eye out on her husband to avoid him being mean and horrible towards his own nephew, and what are some ways to keep the peace between my family if my uncle begins to do his anti- rants towards my cousin and right in front of the children as well.