Kayla, in that situation I too would have hoped that your father would try to pacify your elderly great aunt, change the subject or tell her in a strong manner to stop. Unfortunately she continued unabated, which then upset you. I would not worry about your boyfriend, he spent the time with you to calm you down and make sure you were ok - he didn't have to do that.
I was going to troop out the party line that people get more conservative as they get older then I spotted a magazine article, http://www.livescience.com/2360-busting-myth-people-turn-liberal-age.html
, on an American Sociological Review October 2007 paper about people actually getting more liberal with age however
' "What we believe has happened, at least for the race relations, is that the older group, starting out at a position of significantly more negative feelings, had further to go," Danigelis told LiveScience'.
Your elderly great aunt may have different values from you, perhaps from her upbringing or life experience, and so, as the article suggests, may have 'further to go'.
To avoid similar upsetting situations in the future, a member of your family may wish to speak to your elderly great aunt, explaining that she upset you and why.