Dealing with a Bully via Facebook Message?

[ArtsySmartsy]

Last school year, I had a really tough time with a bully. She found every excuse to pick on me. She's one of those insecure types who needs to push down others in order to feel strong. She was in my group of friends last year, and because I was friends with all those girls, it was hard to escape her.

This year, I've stopped being friends with everyone in that friend group and moved on to different people. She and I don't hang out at all anymore, so she doesn't bother me on a daily basis. But, she still tries to whenever she gets the chance. For example, I was walking down the hall, and she and one of my other former friends were standing close by. The other girl ignored me, but the bully gave me a long, hard dirty look. I didn't know what to do, so I just ignored it and walked on.

One time I was outside, talking to my mom on my phone. The bully and this same other girl walked by me. After they pass by, the bully looks over her shoulder at me, makes it obvious that she's whispering something about me to her friend, and then starts giggling. Again, I didn't know what to do, so I just ignored her. I wanted to roll my eyes at such immature behavior, and I didn't want to get worked up over it because it was so obviously stupid to me, but it felt equally stupid to just stand there and do nothing.

Our interactions are getting rarer, and so I may just never see her again. However, I still feel the need to form some sort of closure with her.

So I've been thinking about sending her a facebook message. Mostly, I want to call her out on her behavior, and make her aware that I know exactly what she's doing. I want to tell her that what she did was not cool, that I won't stand for it, and if she does it again there will be consequences. I know a little about her story. Her mother has been really mean to her her whole life, thus making her insecure, thus creating the need for her to take her insecurities out on others. I'm thinking I can use this as leverage and give her the it-looks-like-i'm-being-nice-but-i'm-actually-being-condescending message: "Sweetie, I know it's hard having a mean mom, but you can't use this as an excuse to verbally pummel others," or something like that.

What do you think of this idea? Do you think it's good, or is it totally awful? If it's totally awful, what would you recommend doing instead? Do you think the idea needs to be tweaked a bit? Does anyone have any experience dealing with this? Any (respectful) responses would be gladly appreciated.
Some parts of the above message got deleted. In the second-to-last paragraph, I meant to write: "it-looks-like-I'm-being-nice-but-I'm-actually-being condescending message:"
AHHH!!! "actually-being-"

[Jarome]

the reason these events are becoming rarer are because your ignoring her, Bullies want a reason to bully you even more so if you send her that message your just adding wood to the fire instead of letting the fire burn its self out.

[Missinglayers]

I wouldn't say anything to her because that will invite her to go out of her way to bully you more. You already know why she is the way she is, so you don't really need closure. Sometimes the urge to speak your mind can be a good thing, but in this circumstance I wouldn't recommend it. The less interaction you have with this girl the better. Trying to explain your feelings to a bully is like throwing gasoline on a fire. She will do everything in her power to try to hurt you emotionally. Don't open up that door because she knows what she does to you is hurting you and she knows it's wrong. You can't fix people by telling them the error of their ways. You are already doing the right thing. Be strong and keep ignoring her. Hang in there!