well I also think you need to give yourself a break. stop apologizing for what your brother did. its off your shoulders dear. Your not responsible for his actions, and its certainly not right that you be the one left to deliver apologies for his actions. your a victim too in this. you lost your brother. I hope you and your family can find peace. maybe now knowing that the officers (in my opinion) used restraint, and followed procedure to a T, it will help you with the long healing process by accepting this was the only way because of your brothers bad choices. thats his fault and not yours.
What he said X 1,000,000. I doubt you'll ever fully understand why he did what he did that night.
Now you should stick around and become better prepared to defend yourself if you were to ever find yourself in a situation like that. You would have never thought your brother would be capable of doing this, now look around and see you just never know who's capable of something like this.