Sounds like he gave you an "answer" loud and clear. I'm the worst at "breaking up" - if you only knew how graciously I did it when I said I wanted a divorce LOL
but, sounds like the time, if you know he's not the one, and then he followed through with a behavior that gives you the strong signal you are right for you.
Something simple will probably be best, but how to phrase or what to say - I am not eloquent enough - Hopefully Anvil will come along soon, she is good with words and now is in a class too
Good luck with whatever you say/do - my only "advice" is K.I.S.S.
(((hugs)))