It’s like the boy who cried wolf though isn’t it?
She lied before about having a terminal brain tumour which in itself is despicable. But having done that, it’s very difficult to have any credibility when you talk about having another illness, because people are likely not to believe you.
people probably already have the measure of her if they’ve already been there with the brain tumour lie, so a lot of people probably are just nodding and smiling and giving out mock sympathy while at the same time thinking that it’s probably not true anyway behind her back.
In her case I would refuse to discuss it any more. After all, she’s cured now, so it doesn’t need talking about.
And then I would put my foot down re financial contribution or tell her she needs to move out.
If I found out that someone was actively lying to friends and family about having cancer I would out them to the people they were lying to.
As for saying you’d do nothing because they “must be unwell,” this is the get-out for all despicable behaviour these days. Even if someone is mentally ill, that doesn’t give them the right to do whatever they want without challenge or consequence.