Sounds like it's time to sit back after your nice little email to her & let her be the next to apologize. If she doesnt then I would definitely accept that there is a time & a season for everything under the sun. Sometimes long time friendships just do disolve because we do change & grow over time....even growing out of friendships that were able to be tolerated in our younger years.

Let her make the next move if there is to be one. That term....."the ball is in her court"would be appropriate right about now.