Sending stuff back to ex. What kind of note to include in the package?

My man broke up with me about 2 months ago. We lived together, had plans on spending our lives together, etc. To make a long story short, he dumps me, packs my things for me (inadvertently including some of his belongings), has a new relationship and I am heart broken. I called him out on his cheating and then he got very mean - saying the worst things you can say to another person. I was saddened and shocked by the way things ended after we lived together as long as we did. It's left me feeling a lack of closure in a way because it was just so odd how things ended. How do you leave things so terribly with someone you were supposed to have loved? Anyway, I am moved into a new place and found some important items of my ex that I intend on sending back. Some people say to not put any note in the package, others say to keep it short saying 'found these things of yours' and I am almost considering putting another kind of note in the box just to give myself some closure. I think that would be kind of stupid and maybe in the long run make me feel worse if I get no response (or even if I do get a response... the whole thing makes me feel lousy). What kind of note should I put in the box? Thanks for your advice.