If she is as you say, she might need to be institutionalized. Is she in therapy? If so can you talk to her therapist, if she is as you say, she is not in right mind and needs to have someone make decisions for her and then you should be able to talk to her therapist. You should be in therapy as well to learn how to cope with this. If she really is delusional this is bigger than what you two alone can handle.