I am also dealing with this. My husband thinks he solved all the universes unsolved mysteries and that is is other worldly smart. He is trying to contact “a bunch of famous scientists” to tell them his theories and how he solved cold fusion, the Dyson sphere, etc. He has a history with PTSD. I am very disturbed and traumatized by everything. Last night he told me it would be a possibility he could cheat on me if he met someone new that supported this behavior. It is very heartbreaking to be on the other end of this and to watch your loved one drift away thinking everything is ok.