I really enjoyed saddle_tramp's "The World Belongs to Me" Series. It doesn't heavily feature mean!Pepper, but starting in either the second or third story, it does deal a lot with a semi-suicidal Tony caused, in part, by Pepper's callous ending of their relationship. There's also several moments later in the series that feature Phil and Clint protecting Tony from her.

I totally get your POV about Pepper though- some stories make me fall in love with her, but sometimes I just don't get the Ironman3!Pepper!

http://archiveofourown.org/series/23119

Good luck with your search!