Oompa I feel for you, but imo she is not an evil twin, she is your wife but she is brainwashed and that makes her have two personalities.They all seem to be like that.
I saw it in my MOM who I loved dearly but she drove me crazy when the Jehovah personality immerged, she would be talking normally and treating me, my kids and grandkids like any other mother/grandmother and suddenly she would bring up JW religion crap. She would just drone on and on but You don't dare interject with something negative against what she was saying. Her eyes would just glaze over and she would keep repeating the same thng over and over not listening.
I used to just change the subject and bring her flowers, bring out family photo albums, make her something nice to eat, take her out to lunch (she loved that). I treated her boring cult sermons with change the subject and lets do something fun/nice.
Have a great day Oompa and I do feel for you and your situation
Velvetann