Old Coworker Wants To Leave Me Her Estate And 20+ Rescue Cats, What Would That Entail?

Hi all! I had a chat today with my old coworker when dropping off Christmas presents, and she said she wants to leave me her estate. Her son is a multi millionaire and she says he has the devil in him. From what she's told me, he'll just kill off the cats and sell her house and never think twice of it. Her relationship with her daughter is just as strained if not worse, so she's out of the question too. She wants to leave me her house (currently valued $240,000) and what few belongings she does have left and she wants to make sure everything is iron clad so that neither of her kids can fight it and it can just be done and as painless as possible. She's 74, family history of cancer and her only remaining family in this state is dying of leukemia. I asked her if she was telling me this just to get her ducks in a row or if she's worried something will happen, and she didn't answer. I just need insight on the logistics of it all. I've never been left anything from a person passing away, let alone a mortgage on a house with $100,000 down, and $108,000 left on the mortgage. Please help