Should I be worried??

Recently I've been hooking up with this guy at my school just cause.. But we never really talked about our feelings until yesterday and he only got comfortable cause I have a history of going to the mental hospital.... Thinking I would relate to him..?? But there was one thing he told me and it just threw me the fuck off

He told me if he were to shoot up a school he'd already have it planned out.. And he was so detailed and I mean it. 

I don't know but he has a lot of red flags that just made me uncomfortable, I'm only friends with him just to hook up. Should I break off contact??