Obsessed mother breastfeeds her adult son

Hoping to find peace and quiet, a young writer rents a room in a house by the lake. Upon arrival, he discovers that the house is actually a bunker, but he still decides to stay. After this, the very strange owners of the bunker begin to beg him to give lessons to their eight-year-old son, who, according to them, should become President of the United States. Soon the guy discovers that the owner is possessed by an unknown creature and she continues to breastfeed her mentally retarded son, who looks much older than 8 years. But these are not all the oddities that the new guest will soon encounter.
The name of the movie: