AITA for refusing to give up my window seat on a 6-hour flight for a woman so she could sit next to her sister?

I recently took a 6-hour flight and booked a window seat because I get anxious flying, and the window helps me feel more comfortable. When I got to my seat, a woman asked if I could switch seats with her so she could sit next to her sister, who was a few rows back in a middle seat.

I explained that I really needed the window seat for my own anxiety and politely said no. She got visibly upset and said I was being selfish. The flight attendant even asked me again if I was sure, but I stuck to my decision.

The woman ended up sitting apart from her sister and gave me dirty looks the entire flight. Now, I feel like the family is making me out to be the bad guy.

AITA?