I'm 58 so have been there, done that :-) I don't think you should be quite so "understanding". Your wife's bad behavior is still bad behavior, no matter what the cause. You should tell her how you feel and insist she get help, tell her you will not put up with ranting and raving and downright bad behavior, no matter if she is sick/well/what the "excuse". If you want to enlist her mother's or other female family member's help; tell your wife you are going to do so and then do so (if she doesn't get help for herself first)!

Don't try to diagnose her yourself with alleged Internet "knowledge", I would find that maddening too; concentrate on only telling her how her behavior makes YOU feel. Let her know you love her dearly but the behavior has to go; you all live there too and "majority rules" :-) "Go to the doctor and/or get help or. . . ." and then follow through.