You know, a lot of people only consider 50 the half way point. If you start living a sober healthy life who knows? That is a very long time to just throw away as so many people would gladly have even half of that.
Take this moment as the beginning of the rest of your life. It starts here, forget about all the strife and turmoil you have had. That is in the past, live in the future. Make life worth living, in the end you will be glad you did.
Hang in there, it really can get a whole lot better if you want it to.