<human>: Can you provide a brief overview of the text?

My brother got in legal trouble and is now on probation.  It has put a toll on my family, especially my parents.  The trouble was not drug related but now he has to take drug tests and can't drink until he is off in June. 

My best friend and I go back to grade school.  I pretty much see him 5 days a week to hang, workout, party. My best friend knows that my brother is in a legal situation.

Anyways my brother and I were driving home one night from a game and I had his phone for directions.  I saw a text from my best friend and decided to open it because why not.  I then see a string of conversation going on how my friend would sell dimes at a time to my brother.  This has been going on for at least 2 months now.

My brother does not know I saw this and I'm not sure how to handle it.  I dont have anything against smoking and I know my brother enjoys it because it helps him relax.  He is a very anxious person nowadays.  Although he has a good job, his life has been in a rut for the past year so I feel terribly bad for him.  However I cannot help feel that he is being selfish.  If my mom or dad found this out it would destroy them.  Knowing that one failed drug test can put him in jail I just dont understand his rationale.  

So my question is how do I approach it? I feel that I should tell my best friend to stop doing it first, then talk to my brother about it.  I obviously dont want to tamper with either relationship because I could not handle it right now.
<bot>: Best friend selling weed to brother who is on probation and gets drug tested and I am unsure about how to handle situation.