Hey Spy,
I think you mean when your mother was talking AT you.
You sound paralysed, attached to the phone by a powerful magnet. Helpless when she calls, not able to say, I have to go now, can't talk any longer. This pot's not calling the kettle black. I know extricating myself from Nmom's babble after work is like pulling my feet out of quicksand, every evening. But it's getting better. I've found if I just say firmly but in a polite voice, I'm heading to bed now (never mind that it's 7 p..m) and follow on, no matter what she's saying, with "Good night, have a good sleep" and then start WALKING, she subsides.
Maybe you could find the phone equivalent to end those calls faster and sooner and before your misery builds? It's an unrequited love or yearning, and from child to parent it's so very powerful. I know this sounds foolish but I think the practical step by step advice in the little book Don't Call Tat Man might help you with this.
It's amazing how Ns can drain the strength from our knees and paralyse our will. (But that's why people write books like that, because there are so many people who need help snapping out of the trance state. No shame in that whatsoever. It's a powerful biological urge to try to get what you need from a parent, and takes a long battle to persuade your inner child to let it go.)
Here's wishing you calm and phone control. (The timer thing, might that help too?)
Love,
hopalong