Just remember that during the fall your body will experience a natural large surge of adrenaline which will pair very badly with the SI realisation at the permanency of the action you just committed, making your last moments the most horrifying and fear filled of your life. I cannot speak on how high a fall must be to take a life as I do not know, but even if you don't survive you may not die instantly when you hit the ground and could suffer for minutes while awake. Also, if you do survive, the odds of experiencing life-changing disabling and chronic pain inducing injuries is very high.
In addition, you wouldn't want there to happen to be someone walking beneath the window when you jump, as you could land on them, killing or permanently disabling them.