Should i still talk to this guy?

Ok I have a friend who right nows in the loony bin because he kept on talkin bout seeing Aliens in the sky,the government makin 9/11 up,meeting a complete stranger online then saying he was gonna get married to her and have kids,not getting a job after highschool because he though he could make it in the NBA and finally because he thinks he's Michael Jordans son. I was really good friends with him in the past but now he's just mentally unstable so I don't know if I should still be his friend or just forget about him. I feel guilty too because I think part of this is my fault for not taking him seriously and flat out calling him insane when I could've helped him. What should I do?