Help! Bridesmaid dress issue

I'm getting married Sept 19, 2015. I haven't been stressed out, until now. My bridesmaids had to order their dresses by April (the latest). My MOH stepped up to make sure all of my ladies had their dresses ordered, all said they did. Well, one of those BM lied, and called my MOH yesterday saying she tried ordering the dress now and Davids Bridal said it's no longer available, and there is absolutely nothing they can do (another issue-why didn't David's call me to let me know not all of the dresses were ordered?!?!) I'm sure how to handle this situation. I'm upset, frustrated and angry that my friend lied in the first place, with no reason why! Now I have 6 girls in the dresses picked out and don't know what to do about the 7th. This isn't my first issue with her thru this process but certainly the worst. I feel our friendship has drifted-havent seen or talked in over a month. Do I let her know how hurt I am and tell her I'd prefer her be a guest at the wedding instead??