Why does it hit so hard?

So I split up with my very abusive ex 9 months ago. And I am so happy now, I got my life together, some money left over at the end of each month, etc,

He text me this morning, very cold message to ask me to remove him as a means of contact as he was getting messages from my mobile provider. I took out a contract for him two years ago, then he took over that contract in the end, and I didn't think anymore off it until he text asking me to remove him off my account. I didn't even know he was on there as main contract. So perhaps a warning to others as he may have been getting notifications from my provider and I didn't even know until he told me. Yes I am getting a new mobile delivered to me today, so he knows what time and also where I live. I have called my provider and this has now been amended.

But his message was cold, and it hit me how cold it was. Why? I don't want him, he is a user, very abusive and just generally nasty.