I'm going to throw my ex's stuff away
What kinds of things are you throwing away?
All the stuff he made for me when we were dating including letters, cards and photos
It's okay to want to get rid of mementos from a failed relationship. This is a way for someone to help themselves move on. Just be sure to return any items that you think they may want to avoid any drama in the future.
It's all trash. I don't want to give it back.
I still think it might be good to give back his stuff. If you were living together and you throw his things away he could take legal action and sue you for damages. But feel free to toss everything else.