So. Old lady here! I was with a guy for years, we were engaged, paid a deposit for our wedding, set a date. Then I realised I didn't love him and I had to end it and it was awful. He hadn't done anything wrong, there was nobody else on my part, no cheating etc, things literally had just changed. I wasn't excited by the relationship, I was just bored and couldn't imagine spending the rest of my life like that. After he moved out we didn't speak for a while, but eventually we did and we're still very close. He actually messaged me a few weeks back and was so nice that I almost cried, one of my friends declared he must still be in love with me (immature, younger friend), and I had to give new bae an explanation about why I didn't marry him because "he's so nice!" so yeah. I can believe things have just changed in his eyes and that's why it's over.
Second part, the way you handled it. I understand that you're upset, but the thing that really irked me was you saying to him "what you gonna do, hit me?" which, unless he's actually done that (in which case you're better off without him) is a nasty thing to say to someone. Perhaps it's because I'm viewing it as a victim of domestic abuse, but it is both a horrible sort of accusation and a very immature and inflammatory response that almost sounds like you're daring him. It's possible that he will come round and forgive you for what you said, but you handled things badly and if I had a break up like that, I would have no intentions of talking to the person any time soon. Even without what you said, space after a break up is an important thing. As for your things, I'd message him and ask calmly if you could get them back or maybe even get a mutual friend to collect them, you have every right to get your things back but there's no point having an argument or anything.