In the future, if you can not act like an adult, please do not attend private family events at which you have not been invited or wanted. If it was your intention to comfort Robert, be there to honor Jean, or comfort his family, you did not accomplish any of the three. Or family functions are not a place for you to feed into your selfishness.
In case you might have actually been attempting to do the right thing, in the future if you feel you must attend univited and unwanted, act like an adult. I may have certain family functions here where I would not exclude you, unless you feel you can not do this. You or dad will receive an invitation to these if you are invited or wanted by other family members to be there.
Jean was a very special woman who loved me very much. She was also aware of my relationship with you, especially since she is the one who offered her home to me 18 years ago after the incident. She would have been saddened to see you and dad walk by without offering your condolences. To her her family, and extended family were her life's joy.
I didn't need your condolenses, but Robert and his family (who also know the story) were shocked to see your behavior, and not even a short sentence of condolence towards me. If you will remember, when your mother died, I wasn't talking to you, but I called you up to offer my condolences. For me, it just highlights what I have been telling them about your attitude towards me all along.
You might consider penning a letter of apology to Robert for your behavior and for the last conversation with him where yyou said "but I had your parents over for dinner" in which you also had no problem breaking ties with him, that is if you really felt like offering some comfort.
PS both of you should know that Robert's e-mail address is in the family calendar, and you should use that if either of you need to correspond with him, and not my address.