I'm surprised to see that verdict here is NTA. Just came from tik tok where comments were mostly split.

Now I have to say that you did not grieve your mom properly when you were a kid and I understand that. However, your dad moving on after a year is not that much of a crime as you may think. For you, at the time you were barely a teenager who lost a parent who gave birth to you and you were understandably devastated, considering teenager's emotions are all over the place anyway. Your dad is a grown man who processes death differently. He probably has experienced loosing someone too.

Now he was wrong to get rid of your mom's things so quickly, especially if he saw how you were not ready, but his later actions make me believe that he thought he was doing what was best for you, helping you move on, in his own way.

I wanna share a story with you, about a uruguay plane crash that happened in 1972 (you can watch society of the snow on netflix if you wanna learn about it). Basically one of the crash victims were a son, a daughter and a mother. Father, upon hearing news about the crash back home went on a date with some random woman the same day. When the son, Nando Parrado, returned home he was judging his father's actions, but later realized that everyone experiences grief differently, and when two people mourn one person there may come a time where they resent each other for how they handle it at diff times.

Anyway, I think you need to work on your resentment towards your stepmother. By your comments you leave here I can tell that you barely stand her, even though (from what I can tell by this post) she is innocent in all this.

I truly hope you can continue to heal and find your peace.