That does sound like it would be frustrating. It's very hard when someone uses emotional blackmail--my mother has said/done similar things and I know how exhausting that can be.
Have you had a chance to check out any of the lessons here? One that has really helped me is SET (Support, Empathy, Truth):
TOOLS: S.E.T. - Support, Empathy and Truth. It's a good tool to use to validate your mother's feelings but also set some boundaries with her. I also recommend to any child of a BPD mother the book
Understanding the Borderline Mother, which explained why my mother behaves the way she does in a way that amazed me.
Sometimes it's good to take a time out. What would happen if you suggested to your mother that you need a break from talking on the phone for a few days?