<human>: I've been working for a rather large company for the last two years. It was basic customer service crap, answering phones, etc. Monotonous, but it paid the bills. I quickly grew disenchanted when the "promises" of upward mobility within the company turned out to be crap. My manager, who was pretty decent, went to a different team and the new one we got is a pretty big bitch. Essentially her role is to weed the team and get rid of as many of us as she can for "cost management." She started riding me pretty hard about work and yes I would actually do my work, I wasn't slacking. However, it got to the point where she was clearly playing favorites, and the last person to call her on it, wound up without a job. 
This all came to an abrupt end last thursday morning. I got to work in the morning and I had yet another email from her and her brown-nosing lackey about something I supposedly didn't do (which I did). I walked out. I don't completely need the job and have something else lined up now, but because I just packed my shit and left without saying anything, things are unclear with the company. Manager keeps calling and leaving me messages and now has resorted to emailing me to my personal address. 
Reddit, do I do the grown up thing, and reply to her email or call her and just say I quit, or do I write her an email and completely tell her off and possibly copy some of my ex co-workers. Keep in mind that the company has no way of hurting me anymore.

Summarize the given text in a few sentences.
<bot>: company/manager treated me like crap. got fed up and walked out. manager keeps calling/emailing. Should I be a grown up, or tell her off in an email like I always wanted to?