You've already gone through a whole slew of advice...so I guess you need mine as well
I was roommates in college with one of my best friends from high school...bad bad baaaad idea. Before the freshman fall semester was out, we weren't talking anymore, and I claimed I was done. In the spring of my junior year of college she tracked me down and called me, and I figured, hey why not, I wasn't living with the b*tch anymore, we could be casual acquaintances. This continued for six years. Until the week before my daughter's first birthday. To make a long story short, she claimed she had swine flu, had just been around my daughter within the last few days before she made this claim, yet refused to discuss how the ER came to this diagnosis and proceeded to tell me if I was worried I should take my infant in to have her tested. Her reason was "well, usually when babies are sick they cry, so your child must be ok." Needless to say, I cut her off again.
The important thing, I guess, is whether or not your friendship is worth the hassle. People do change, but often they keep a fraction of whatever it was that made you end the friendship in the first place. The hard part is determining whether you can deal with that, or whether you'd rather move on. My child did not have swine flu (because the b*tch didn't really have swine flu; she had some kind of gastrointestinal upset and lied about the diagnosis to throw a pity party), but that doesn't make what happened something I am willing to move past. There is a difference between forgiving and forgetting. I hope you come to the right choice for you without regards to anyone (including us geniuses here on ye olde internet) say about it. Good luck.