I wasn't being particularly abusive about him. In case there is any doubt, I quoted his whole email without parentheses. He said that about me (both lines). He was calling ME a low life because he was implying I was misquoting him. The sensible thing of course would be for him to respond with his original comment, if I remembered it wrongly.
I quite regularly use or utter the word a**hole in my mind to describe slow and incompetent drivers, certain DHL delivery men, lazy slobs and people who have no respect for themselves, so he's getting no special consideration from me.
I just wanted to mention his email in case others got similar.