I didn't want to hijack Shatzie's thread (and BTW, Shatzie, I think you handled the situation very well), but a question did occur to me.
Toxic relative (let's say, grandmother) is notorious for having meltdowns at family gatherings. Always has been, and if Toxic grandma has her way, always will be. Other relatives who usually act as host/hostess know that Toxic Grandma will behave like this, but after a lifetime of trying to kowtow to Toxic Grandma, will always invite her to the party because they cannot say no to her.
But what if there is a guest of honor for the party, someone who would love to exclude Toxic Grandma from the guest list. In Shatzie's case, she had just graduated. But it could be for other reasons: wedding, funeral, baptism of one's child.
Does the guest of honor have the right to say to the host/hostess, "Please, since this party is for me, please do not invite Toxic Grandma. If this party is to celebrate my accomplishment, I do not want Toxic to ruin it with one of her famous tantrums?"
And if the guest of honor is not rude to request this, would it be okay for all situations, or would certain situations be exempt? The reason I am asking this is because I was wondering about weddings, They seem to be so important that excluding someone would be a major insult, and capable of tearing the entire family apart.