A lower-lying tenet of DBing is "Do not assume" and your stance about his relatives has many assumptions intertwined with your decision-making. Be careful with predicting other's behavior.
I remember seeing an 'ex'-uncle who had D'd an aunt many years ago at my GM's funeral 2 yrs ago. It was surprising to see him there. He commented that no one told him, and that he had to take off work that day to race over to pay his respects to his ex-MIL. I and many of my relatives communicated our appreciation to him for this act of respect. You and Andy have much more positive feelings toward each other than this uncle and aunt had toward each other, even years later.
Having said this, I respect your decision to avoid his funeral.
