I would experience it as though she could be mad also. I would definitely bring it up, as difficult as that might be. The part that you wrote which stood out to me the most was when she said you can't expect her to answer the phone when she is with clients, as though that it what you were asking her to do. As long as you haven't asked for such a thing or shown anger toward her for it, I think it is HER issue. She could be projecting her own stuff onto you.

But the only way to resolve it is to talk to her directly about it