I used to get the same kind of treatment in phone calls from my mum.
Every call, no matter how it started, would at some point change to talking about my brother and how mean I was to him by not 'helping' him.
I stood my ground for about 18 months.
My relationship with my mum is probably the best it's ever been right now, and it is good, and I think it's because I did finally stand up for myself and proved to her (and myself) that I am my own person and can and WILL make my own decisions.