Can I update my iphone 5 to ios 8.4 now that ios 9 is out?

I want to update my new iphone to ios 8.4.1 because it has ios 8.2, but i don't want to update it to ios 9.0.2 because my brother did that and his iphone 5 stopped working. So how do I update it to 8.4.1?

Nope. There's absolutely nothing that you can do. Once Apple stops 'signing' a previous version of iOS, there's no way to ever go back to that iOS version.