"Impossible to see, the future is." - Yoda

So why did Luke try to murder Kylo in his sleep over a vision he had? Is that part of the film even remotely believable?

1. Luke knew he could only see a possible future, not the actual future.
2. As a teacher, Luke knew his students might get tempted by the dark side of the force. Sureley his solution to that problem wasn't to kill those students.
3. Luke was Kylo's nephew, even had Luke been the murdering type, you don't kill family easily.
4. In real life, pretty much nobody kills somebody in his sleep, especially not a child.

I would find the reasons for Luke's actions hard to accept even in a normal person and unless there's a big gap in the story and something else happened to Luke that made him act in such s way, I just cannot accept it.