How should I deal with a two way betrayal?

Recently, my younger brother left his phone in my room to use my charger as he lost his. When i saw it I went through his messages. From these messages i found out that he had been smoking marijuana with his two best friends, and that he was getting the weed from one of his friends who frequently stayed over at our house and was like a part of the family. The messages went into detail about how he had it in our house and was frequently smoking it at a nearby park with his friends. My brother had told me that he tried it about 4months ago but after I spoke to him he swore it was a once off, so when I saw the messages I was shocked and really angry. He is only 17 and doing his VCE this year. I was completely torn about whether to tell my parents mainly because of how I found out and I knew it would ruin our close relationship. I eventually decided to tell them. It has caused so much tension, hurt and upset within my family. My brother is in an insane amount of trouble and has lost heaps of privileges. It has been about a week and he still hasn't spoken to me. I'm scared I’ve done irreparable damage. The trust has been broken on both sides. I feel rotten about what I’ve done and completely guilty but I want him to know I did it because I love him so much and care about him. I’m still angry and totally confused as to why he has done this. Do you think I did the right thing? How should I begin to fix this? Do you think that what I did was just as bad what my brother did?