Re: loosing control
Story of many parents raising teenage kids.
This didn't happen over night - there is nothing wrong with hanging out with non desi friends but you need to make sure that you are aware of the activites he is up to WITH ALL his friends.
Open the lines of communication so you understand what he needs right now.
It is tough road to introduce religion, culture, respect at THIS AGE. Those things need to be intiated very early in life.
You won't know if a girl is involved unless you ASK him or desi style investigating