I'm gonna hijack your top comment spot to say that I think this situation is sadder than people are giving it credence for. The woman lost her life partner, and is obviously grieving in a weird way. She knows she is too old to start over, but she wants to feel that kind of attraction again before she passes. I don't blame her, but she is wrong for going about it the way she has.

She is harming not only you but the person she is catfishing. If you all care about her, I suggest some sort of family intervention. Reiterate that you love her and care about her and want to spend your time with her, and she could just get over this other thing.

If you don't care about her than you can just tell her to go fuck herself, I guess.