Sister's Fight! What should i do?

I have 2 sisters, they each have 2 kids. 6 months ago at a birthday party they called my daughter names and said that she will not do well in life as she has add. She was playing with the curtains and running around with 2 other kids. i never have had any probs with other people's houses.
I have been to doctors and they say she does not have add and is just very active.
They wanted me to come over to there house for a party and i said no because i felt uncomfortable with my daughter being such a annoyance. Now they say that i am bitter and are using my daughter as a play to hurt them. Am im in the wrong should i just forget it all or should i just stay away. I told them that i was upset by what they had said.