Though I think the mule is just as guilty as the scammer himself, and she should return money to Lilian. The excuse that she "spent the money" is ridiculous. If she has sent that money to a scammer already, she should return her own money. It's a mule who should be out of money, not a victim.
I repeatedly expressed that point of view on RS:
https://www.romancescam.com/forum/viewtopic.php?t=46368#p250324
In your case, I would sue. I am not sure if you will win, depends on how the judge looks at that. If the judge has my point of view, you will win. If the judge is sorry for the idiot, you might lose.
More on mules:https://www.romancescam.com/...php?f=77&t=56329