<human>: Can you provide a brief overview of the text?

Sorry if this is a bit of a ramble. I just want to make sure anyone who gives an answer has enough context to help if they can:

A year ago, a girl I was really into dumped me and strung me along for a while after that. Now she's sent me an email simply saying "How have you been?" I feel this is inappropriate for two reasons. First of all, the break was really bad. We both said some pretty hurtful things and I was definitely the one worse off for it. I've spent a lot of time trying to be more emotionally open to relationships since then, and it's always failed miserably. She, on the other hand, has been dating another man since two days after we officially broke things off. Secondly, for the last 14 months she, at least, has been content to pretend as though I don't exist. Any time in passing we've seen each other, for instance, would be as though a complete stranger had walked by me. I can't deny that it hurt a little, because of course it does, and this email just reminds me of all the hurt I felt. 

I am at a loss of how to handle this. I feel like she's definitely sending this because she's graduating and not because she actually cares about my feelings. She was never shy about having me aroundto comfort her after the breakup/whatever she said she was going through and then tossing me aside once a new guy was in the mix. I was totally used and completely devastated. 

Should I email her a brief update tomorrow morning? What has anyone else's experience with this been? Is there any way I'm not looking past my old hurt and being stupid by NOT wanting to respond? Is there actually a healthy solution to this that I'm possibly overlooking because of my feelings? I don't want to regret doing nothing, but then again I'm afraid this could just open up old wounds, and I really don't want that.

Thanks for reading if you made it this far! I really appreciate any and all advice :)
<bot>: Ex emailed me out of the blue. The break-up really hurt me and I'm not sure if responding is a good idea. Any advice?