No m8.
When you're actively running away/retreating and being chased by multiple people, one of which threatens to shoot you vocally, and then you trip over and one of them attempts to put a skateboard around your head. And then another pulls a gun and points it at you from close distsnce - but suddenly points his gun and hands up and moves back when you raise your ar 15 in response to this threat, at which point you respect his 180 turn around where he is implying 'actually, i dont want no trouble' , and lower your gun. only for him to then - once your gun is lowered and you look away breifly, assuming he is being genuine, notice he has now raised his gun at you again and is advancing once more, so you then shoot him.
Thats not self defence at all, lol.