Oh no, these are very bad news!
Please tell your friend I'm feeling with her. (((HUGS))))

That's one of the "bad" things about cats, they won't let you know they are sick before they are in a real bad condition! Poor poor baby!

You asked how we would decide...
Well, I think if it was my baby, I think I would let her go to the RB. I know how hard this decision is, but I think everything else will be pain, suffering and fear - not only for poor Luba, also for her mommy. She would have to face the inevitable day by day, and I don't think with force -feeding and that tube, there would be much life quality left for Luba.

Keeping your friend and little Luba in my thoughts,
Kirsten