Should i reply to my ex or carry on no contact?

I had to break it off with him 5 days ago because he told me he wanted space. Would come back tell me he missed me and go on as normal. But if i asked about us he'd say he wasnt ready for a relationship, the demand of it. I waited for nearly a month for him to be sure about me. So I ended things and he didn't even TRY to change my mind.
So I deleted and blocked him off everything except iPhone and I get a message that night asking why i deleted him and i said i dont want things to drag on and he just said cant we be civil? I said that we could be but i dunno if ready to be to which he said alright. I haven't spoken to him since then…
Today I get a message from him saying "Are you alright? I'm worried about you. At least text me so I know you're alright"

Now, I'm not a danger to myself. I'm fine. We have mutual friends that I've seen around, as we go to the same uni. I haven't even cried about this situation. I admit I want him back, but I'm getting confused. One minute he wants space, the next minute he's worried…

Can someone maybe tell me why he's doing this? Also should I reply?

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