I don't know your story; if she's disowned you, how do you know if she still lying?
And this isn't a flippant question, but I'm really interested because I deal with this too, and think maybe there's an issue behind the issue (or maybe not), but...why does it matter? Why does it bother you, is it representing something else?
I'm not asking to be argumentative or to suggest in anyway it should not bother you. I am applying your situation to something that feels similar in mine (not that they would in reality be similar), and I know that kind of lie coming from a certain person I know would bother me because it represents all the times he got away with it. All the times he was not called out on it when he so richly deserved--needed--to be.
There's a thousand legitimate reasons why this would bother you, and my example is only one. But I was curious because your reason might give me more insight on my situation.
It's as meaningless as lying about your age (I'm really 39, that sort of thing when you are really 45), and it's self delusionary and as PP said, probably she's not fooling many people which is pathetic. But maybe that's the annoying part; the colusion of others. Her lies make liars out of them. And they lie to be polite and avoid conflict...and maybe that's the crux of the situation: we are trying so hard not to fall into that codie behavior anymore, to stop ourselves and get uncomfortable when others do it? Kind of like denying our dieting selves chocolate cake, and then being annoyed watching someone else eat it infront of us?
I'm groping. But it's an interesting topic to explore.