You don’t need to even be mean or tell him anything. Everything you do is opening the doors for further conversations. Don’t respond. “Your words mean nothing”. It opens for him to say “but they meant something when we were doing XYZ”. “Don’t contact me”. It opens for “but I love you so much and I wan contact”. Don’t respond. You don’t need to be directly mean.

Him leaving things is a common occurrence. It doesn’t mean anything. It is hard to take everything. I like to get new things when I move. I’d leave stuff behind or donate or pitch. It has no meaning. Either throw them away or use them without giving it any thoughts.

These are just things. They have no meaning. Unless he left his Oscar or his Noble Price or great grandmother’s diamond ring behind, who cares. Don’t spend a minute thinking about it