Hi Chazak,
First of all,don't get depressed,because it's easier then to fall again. Instead,try to see what you can learn from this fall. I remember reading somewhere (perhaps someone knows the source) that when we feel on the edge of falling,we should fight against it with all our powers,but if we fall,we should see it as if Hashem wanted us to fall. By knowing this,we can get up more easily and also,since everything Hashem does has a purpose,there is something in there for us to learn,right?
My most recent fall was caused by being way too confident that I've got everything under control,which frankly,was just a big illusion...and also it determined me to get signed up here and get support.
Don't worry buddy,where with you. And remember,even after you have had a fall,you haven't lost those days you where being clean. They are you merit. So get up and keep on going. Take one day at a time. That's the only thing you should focus on. Today.
All the best.