I think that it would be very good for you both to give her last chance. I know it might be wierd thing to say but I met a lot people in my life and some of them just don't know better. No one told him what they are doing and how bad it is for the realtionship and for some people... it is only type of relationship they know from home.
If you choose to continue this relationship you have to tell her that it is not the way that you deal with issues in the friendship and you can't continiue relationship with her if it repeats in the future. You friend should know that you want to have loving and sincere relationship with her and you expect her to be honest or even blunt if this is what takes you to fix the problem but you won't accept silent treatment ever again.
I hope everything goes fine