What is this?

My moms boyfriend constantly is thinking they're are other people or men in the house watching him and that they're secretly filming him and making a movie on his life. Last night, he sent her this text while she was in bed.
Now he swears he has a camera and "system" hooked up and couch hear them "fucking". Obviously it's all in his head. Once, he even cut open the couch because he thought there were people in there spying on him. What type of behavior is this? In no way am I making fun of this man but she thinks it's normal cause she's been dealing with it so long but I think it's a serious medical condition. 
They have been drug addicts and still may be, but I think there's something else too it than that. Also she has never cheated on him.
* he acted this way BEFORE the drugs, so I don't think it's that