Rise Above or Sink Below?

I'll just say it: people are assholes. No matter how much we like to think that we're all grown up, most people have a little of that high school gossip in them. I am no exception. In general, I try to do it when the person I'm talking about isn't there, but everyone has a different tactic. Today, someone gossiped about me right in front of me, using code and thinly veiled innuendo. Bitches.

Here's the deal: I had to fire my assistant earlier this year. It wasn't easy, and I felt bad because this girl had so many personal problems. She had two babies, a husband who didn't help much, a teenage stepdaughter who gave birth to a premature baby, etc, etc. She missed a ton of work and had a bad attitude. She spent her days gossiping and just wasn't cut out for the job. My boss hated her, and eventually she got caught falsifying her time sheets. She was out.

Not surprisingly, her little gossip friends think I am a Class-A bitch. They don't believe she did anything wrong, and accuse me of firing her "because I didn't like her." They're right, she wasn't my favorite person, but I fired her because she sucked at her job. End of story.

Anyway, I'm eating in the kitchen today and her little friends come in and sit down to have lunch. We're the only three people in the room. I'll call these ladies I.B. (standing for "Immature Bitch") #1 and I.B. #2. I'll call my fired assistant "Susan."

I.B. #1: So, did you hear that Susan's son has to have tubes in his ears? She started crying when I talked to her. I mean, what with moving, and her new job, to have THIS on top of her too?

I.B. #2: Yeah, well how is her work handling it? Are they giving her time off or what?

I.B. #1: They'd have to, right?

I.B. #2: We'll, stranger things have happened, haven't they? But I guess some workplaces have compassion (said in a very pointed, meaningful tone in my direction, implying that I have NONE.)

The I.B.'s went on right in front of me, basically calling me a bitch as I sat there and read the Local section of my newspaper. Why they're so emboldened and angry seven months after her firing is my question.

I just sat there and pretended to read the paper, as if I didn't hear a word they said. I wanted to turn to them and say something really catty in return, but I bit my tongue (so hard it almost fell off, I swear).

I decided, this time, to rise above the situation. I'll never change their minds, these women (girls?) will always hate me. I can deal with that. What I can't deal with is some disrespecting me to my face. So, what to do? Do I just mentally file this away and interject next time, saying "Enough. I know you're talking about me, and you need to stop." Or, do I go and talk to HR, letting them know that I'm receiving some degree of harrassment? It's so tempting to sink below and do something very high school-ish, but that's not me. At least, it's not who I want to be.