How to stop feeling guilty for not wanting to talk to your mom?

Recently started therapy a few months ago and it’s really opened my eyes to how awful of a person my mother is and how terrible she’s treated me my whole life. We barely talk much at all as of now and I only see her maybe once every few months but I think I’m just over it. I have no interest in talking to her because I have nothing to say to her. Every time I talk to her she just complains about her life and she’s just full of lies and bullshit anyway so I don’t even care for what she has to say. But I still sit here and feel guilty while I stare at her name ringing on my phone while she leaves me a voicemail. I can’t shake it.