Answer:
Hey Aunt [Name],
Hope you're doing well! I just wanted to reach out and apologize for how I treated you during your visit to our house last Christmas. I know I wasn't the best host and I'm really sorry for any discomfort or hurt I may have caused. I should have been more understanding and made sure your stay with us was more pleasant.
I know the holidays can be hectic and I should have handled things better. I'm really sorry and I hope you can forgive me. Let's make it up to you next time you come visit.
Love,
[Your Name]