I really do sympathize with you rutineli, but i doubt if there is much that you can do apart from being there for the lady when /if she eventually sees sense. I am in a very similar situation with the 85 yr old guy next door. Long story short- i've found out he has been befriended by a dead-leg he met in a town centre pub, who first of all gained the old chap's trust by taking advantage of his well-known love of animals. This no-mark spun a sob story about not being able to afford to take his sick cat to the vet, so my neighbour lent him the money, which the guy paid back after a couple of weeks. Very smart move there, because as a result he gained the old guy's trust, and has up to date milked him for between 5 and 10 thousand pounds!! And yes- i have told the police, but as my neighbour refuses to make a complaint, there is absolutely nothing the police can do on "3rd party intelligence".
Good luck to you and your friend x