I know this story. I had a bad patch about 10yrs ago and went off the deep end with nitrous, thinking that since it was legal and easy enough to put down I would be ok with it. Well, I hiding it, disregarding responsibilities, not bathing, losing time, using for 8-10hrs at a time. I know all about the b12 deficiency too, the pervasive anxiety, zero memory, brain fog, it was crazy. It took years for me to get back to something normal. I've done a shitload of drugs in my time and a handful to excess but nitrous was the one that I would say I was strung out on. Fortunately (or unfortunately) I had enough money and time to get high pretty much as much as I wanted so this made it seem as though there was no reason to stop. All I had to do was get it together enough to get to work and do my stupid job so I could get back home to get high. I would sit in my recliner and easily do half a case (600/case) so 300 chargers and have all the empties laying all over the floor. I did this every 3 or 4 days for several months. I finally woke up one day and realized that shit was doing some serious damage to my body and left it behind. I had done so much that I could feel it harming me each time I did it towards the end which made it a little easier to stop.