Hi Charlotte,
it is good to get things off your chest by talking. You obviously are having a really bad time worrying about your brother. If it would help The Icarus Trust is a charity that supports the friends and families of addicts and has trained volunteers that you could talk with. Maybe talking with one of our ‘Family Friends’ would help you to make some sense of it all and find a way ahead.
You can contact us on help@icarustrust.org or visit the website http://www.icarustrust.org
Good luck.