Don't be too hard on your Aunt. Most people (including yourself) are on their best behavior when in public, and are in a better mood when around their friends or on special occasions. It's not just a JW thing.
What makes it difficult to take when it comes to JW's is that they use their loving behavior as proof that they are the true religion when really, they are like everyone else who have their good and bad qualities....good and bad moments of behavior.