I have been smoking MJ for years as well....basically from my 16th till a few weeks ago, had some periods I didn't smoke but basically have been smoking every day.
I loved it and have also been using it to self medicate, as I am bipolar and also have BPD, but the last few months I noticed it only made my depressions worse and the medication I am taking working less.
I am an all or nothing person too and decided to just stop 'cold turkey' which was the only thing that would work for me, I had done this some times before. Just getting to the point of actually stopping has always been the hardest thing for me, every time I decided to stop something happened that made me feel different so I went on smoking. I managed to do it though!
Two days ago though I wanted to smoke again...but when I was actually smoking it felt like my first cigarette, made me cough and my lungs felt really bad, together with that I didn't even get high so that was a sign I did succeed in quitting and don't want to smoke again any time soon. Hopefully this won't change.

If you can do it, I think it's best to just stop 'cold turkey' but try to find something to do/distract you. The first 3 days are the worst and after that it will only get better. I wish you luck!