How long are these withdrawals going to last?

I'm 19 years old and I've been smoking marijuana heavily for almost 2 years now. Probably haven't missed a single day without smoking in a long, long time.. I found that marijuana hasn't been anything but problem in my life and that it's not worth it to smoke any longer. I've been clean for exactly one week today, and it has probably been the most miserable week of my life. In the beginning I never thought marijuana was addicting, and i'm sure a lot of people would like to argue with me on it being an addictive substance, but I believe that addiction to pot is VERY real. These withdrawals are horrifying, I fantasize about smoking every minute of the day, desperate to just take one last hit, but I know I can't because I have a very addictive personality. I've had panic attacks every day this week, headaches that last the entire day, full body muscle aches, nausea and vomiting, not able to eat anything whatsoever. I'm having suicidal thoughts all the time, wishing that this would all just end, though I would never take it that far.. I'm so fatigued that I just lay in my bed all day.. I have a very loving family that cares about me and are trying to help me as much as they can, but they don't know what to do. I already take several medications for anxiety and mood disorders. So really my main question is, how long is all of this going to last? And what can I do to help cope with these withdrawals? Thank you for your answers.