I'm not sure what you want to call it, but it was extremely inapropriate for sure and it wasn't good for you for sure as well. And I feel very sorry for you about it.

I believe that question if it was abuse and if so, which kind of abuse depends on the question what the intention of the abuser is and which desire is fulfilled by the actions.

My late grandfather told his daughter(my mother) on the phone that at the age of 80+ he was still having erections, but that he hadn't touched my grandmother since decades as he was disgusted by her and he would need another woman, etc.

Now, having known him very well, I know this was clearly abuse. But not sexual abuse. This was about his unsatiable desire for being admired. But to get admiration and confirmation how great he was, he needed another person. But whom should he have told it? Any friend, neighbor or same generation family would have scorned him for saying so. Or at least they would have at least shown their embarassement and disgust, so it wouldn't have worked. But he just had to tell someone. So he chose his own daughter to do so. And that's the abuse.

You know, there is this an old joke. I hope you allow me to quote it and I hope you are not offended.
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A young man goes to a catholic chuch to confess. When the priest asks him what sin he had committed, the young man says "Last night I did it to my wife 17 times straight" to which the priest replies "Well, this might be a bit unsusal, but since you are married, it is not a sin". To which the young man says "I know, father, but I just *had* to tell somebody about it".
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So, just a sick joke, but as a matter of fact this man ab-used this priest for his desire of bragging. And this is what my grandfather did to my mother. Same story.

My recommendation for you would be to ask which desire your mother tried to fulfil by doing this to you. From what you describe it could be the desire for excuse and justification why all her relationships had failed. Friends, neighbors, etc. might have contradicted her, might not have believed her and said so and even asked her to stop talking like this and would have turned their back on her if she didn't. But you couldn't walk away and couldn't have contradicted her. This is what makes it abuse to me. But of course I could be wrong about this.