How should I treat an old flame?

Just over ten years ago when I was 17 I met a girl through a friend of my dad's friend. It wasn't really a relationship, more of a prolonged series of chats over the internet and the occasional meet up. She had issues with her mother who, she said, had a disease and only a few years to live or such. This meant that her mother was dragging her out all of the time which prevented her from meeting up with me, though we met up a few times (about 4 times in 2 years). I felt sorry for the girl too as apparently she had sex when she was 10 and then the guy went and told the whole school, so I thought she didn't trust men.

When we did meet, she seemed a little socially awkward, not shy but withdrawn. We'd hold hands, but when I'd give her an innocent kiss goodbye (a peck on the cheek) she'd freeze up. I think there was definitely an attraction, but the lack of meeting up over the two years grew into a bigger issue, I felt like she was just using me for attention and I was really pushed to the limits of my patience (And I'm a very patient guy). Two of my friends ridiculed me. The worst was one time when the three of us were meeting up with our girls (like a triple date in a way) but of course this girl didn't show up, saying her mum had taken her out shopping.

I eventually got really angry and fed up, I pulled the plug. I was going to university soon anyway so I moved on. I have to confess that I kept hope she'd return (I had my 18th birthday around the time we last spoke and I think I had invited her). As I've done with several attempts at a relationship, however, I built up a lot of anger and doubt, either at myself or the girl involved and wondered what, if anything, I had done wrong.

Then this morning I have a message on a dating site that she's recognised me when looking at my profile. I've actually wondered over the years how I'd treat her if I saw her again, I felt like I'd almost explode with anger at how she had mentally tormented me.

So far I've responded saying I barely remember her, though in truth I remember a lot. I feel like being midlly insultive or angry, to finally let her know how the experience messed up my head and confidence, to resolve things ... but I feel like I shouldn't. It's been 10 years, however it's really agitated me now which is why I'm posting this.

What should I do?