Hi,
That guy is not a flirt, he's a cad. A big difference between the two.

I am a flirt and I do it with taste. A true flirt leaves you feeling good about yourself and a bit of mystery about him. Flirting can be and is fun. The boundaries need to be respected. I like flirting because it does no harm and makes people feel good. Leading someone on is not flirting, it is caddish behavior.

Just my .02cents on the subject of flirting.

I am glad you found out about him and then disposed of him.
I wouldn't not avoid his place of work or give him the satisfaction of knowing how I feel about him. I would just be polite and civil to him. That would be oh so powerful because you are rejecting him with out anger.