Hithere
I would concentrate on the human side (not on the number side)
Why she needs this much money?
Why did she threaten suicide?
Why does she need more money?
I find it curious you concentrate so much on the money and getting it back (which you may not) and not on her mental health, given you have/had a close relationship
I would be worrying about the money 10k is alot of money to lend someone even if it is your sister.
It's too glib to say you may get the money you may not, maybe you can afford to lose that money.
The above said I think there maybe something amiss and I would try to fund out.


