The beautiful unknown under the rain

It was a lonely and rainy tuesday night for Mireille, 66YO, when someone knocked on the door.  She opened to discover a young woman, wet and incredibly beautiful. She seemed familiar but Mireille wasn't able to remember who she was.
"May I help you ?
- I was just gonna ask you the same thing, Mireille, answered the unknown with a mysterious (but familar again) smile. Don't you recognize me ?"
The woman moved forward so Mireille could have a closer look on her face. The old lady finally knew why the mysterious one seemed so familiar : she looked like Nadine, her best friend. But Nadine was 66 YO too and, even during her youth, was never that beautiful.
"You're... from Nadine's family ?
- No, silly ! she laughed. I'm the one and unique Nadine. Now, can I enter. It's freezing and rainy out there"
Mireille was so shocked she let this "weirdo" enter into her house. Then, as they were taking a cup of tea, "Nadine" explained to Mireille she contracted the "Beauty Virus" recently as she slept with a friend from her Bridge Club. Even if she will die from it, she was too old to care about it. And she was there to offer the same thing to her best friend, Mireille.
"You... you want me... I mean... "us"... to have... to have...
- To have intercourse, yes. So I can offer you beauty and youth.
- But I didn't know you were... you were...
- Lesbian ? Come on, don't fear to say "words" ! And no, I'm not. Indeed, I prefer men, but occasionally..."
Nadine smiled, took off a strand of her beautiful face and kissed the old lady. Mireille tried to resist but, maybe because of the beauty virus, her best friend had some irresistible perfum, such delicate lips...

Then, the night went.

And the next morning...