It's very much possible this is an intrusive thought. It's possible to come up with any thoughtform in the mind and then things get off the rails like this.
However, it's important to note any thoughtform created in a healthy mind isn't going to do horrible things outside your awareness. If there isn't something else going on like a mental health problem, then "Cade" is likely just spewing scary thoughts and you can choose to reject them.
I highly recommend seeing a mental health professional. If you can ignore Cade and move on that's wonderful, but it sounds like you have a lot going on that needs further investigation therapy wise. If not, a professional can help you put together a strategy for addressing the cause, whether it's intrusive thoughts, delusions, or something else (edited)