You are not responsible for him or anything about him including how he needed to be handled so he'd stop and respect your request of NC. Sure you could have just ignored him but how long would he have kept it up? Likely until he got your attention whether that attention be good or bad.
You are totally self aware, violet. That's a good thing because eventually with practice implementing your personal boundaries, you will not feel the least bit guilty just because you were strong, confident and didn't allow someone to disrespect you. You'll simply tell them and you'll walk away. Your delivery will also improve from being (somewhat) aggressive to definitely assertive. Having conviction and sticking to it will hone your self-worth and confidence so don't you dare feel guilty. He faced the consequences of his action... those are his to process, not yours.
Incidentally, since sending the text I feel completely free of him.
Well done. Consider it a goal met.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion