I'm so sorry to hear about your loss. You know you are in my thoughts and prayers.
It must have been awful for your brother as well. I don't know exactly what I would have done. Right now you will need to focus on making it through one day at a time. Your life will go on even though you may not feel that great right now.
The friend who shot himself must have had some serious problems that you may NEVER know about. Even though we know people, we don't necessarily know everything about them. We all have secrets hidden from those close to us.
Please make a concerted effort to share your thoughts with others close to you, and don't become one who shuts out other friends and relatives. The more you speak of your friend and his LIFE the more you will realize that he can be a turning point in your life for the bettter. Try to celebrate his LIFE instead of his death, by remembering the Good things about his life.
Also, you should tell those around you that you appreciate them and that you love them. Don't postpone today anything that you think needs to be done. Appreciate life in those surrounding you. You will have less regrets if you focus on the lives of those around you. Sometimes it helps to volunteer somewhere. You could become a volunteer at a local hospital working with sick kids. There are a lot of opportunities to help others, instead of only thinkiing about yourself.
Good luck. I know you can become a fantastic help to others.