A mother/attorney called, threatening to sue for child endangerment and slander of her daughter if I did not say sorry to her daughter. Unethical?

Two families went on vacation for high school graduation. 18 year old boys brought their girlfriends. The "couples" seemed to be underlying drama with the girls. The older adults stayed out of it and made sure the vacation stayed on track. By the end of the week one of the boy's mom put herself in the middle of situation and was very passive aggressive to other parents. Both families starting ignoring each other. The last day of vacation as families were leaving the premises, there were words spoken between adults. One of the high school girls was eavesdropping and reported back to her mother that she was being blamed for entire fiasco of a trip. One month later, girl's mother called demanding I apologize to her daughter and the other couple for my outrageous behavior, my bad character, and being a liar. She then said she was a lawyer and is thinking of suing me for child endangerment and slander. I asked if she was threatening me and she said yes. Is this ethical?