Friendship was never easy. The true meaning of friendship is to be there for each other in good times n bad. So take it as a bad patch in your friend's life n deal with it like you would with your own. At the same time give her space and time to heal on her own too. Just don't give her any thing from your side which could make her unhappier. Try your best to understand her and deal her accordingly. For example, if she gets angry over a very small issue you just have to be a bigger person n say sorry and then later when she cools down you try n make her realise that she needs to sort herself out (ofcourse in a much better way :D) but that u r there to help her in any which way possible.
:-)