Need advice on setting boundaries

I’m 23F and have been out of my parents house for about 5 years now (since going to college and moving away as soon as I graduated). I now live 5 hrs away in a another state with my partner and I have an estranged relationship with my parents.

Basically, my dad was very verbally abusive growing up (screamed and berated me constantly) and my mom only enabled his behavior and never stood up for me (would use the classic “I’m telling your father” threat). She was also emotionally neglective and always said I was making her life harder when I was upset about anything.

My dad rarely talks to me now so I don’t have much of an issue with him; I think he understands I don’t want to be close with him. The issue I’m facing now is particularly with my mother…

She texts me every single day and freaks out worrying when I don’t respond. She’ll call me on the phone and go on about mundane things. Its just becoming increasingly difficult to keep up with this act of talking all friendly with her knowing I can’t forgive how she treated me growing up. She never once apologized. I don’t even know how or where to begin to address it.

And I feel terrible sometimes for feeling this way because she’s so friendly on the phone sometimes. Just chatting away about whatever. It just leaves such a bad taste in my mouth because I know how she truly was to me growing up. These conflicting feelings are really whats affecting me the most.

I guess what I want to ask is, how can I set further boundaries with her? I’m not comfortable texting her every day, especially knowing she will panic when I don’t respond. I can’t even understand why she acts like that because we have not been close since I was a young child. Could it possibly be that she’s afraid or expecting me to fully shut her out? I really don’t know.

And if I even attempt to set any boundaries she will probably cause a huge scene and guilt trip me. She would definitely drive up to my apartment too 5 hours from her. I just don’t even know what to do. Can anyone relate to this situation??