@Draconator Obviously, all of us here at TBD are grateful for your friend's phone call! Happy to hear you're healthy and thriving.
I was at a similar point 20 years ago. Had made up my mind to jump in front of a subway car during a mental health crisis in grad school. Luckily, a fellow classmate saw me at the edge of the platform with a glazed stare, grabbed my shoulder and asked me if I was okay as I hadn't been in class for a couple of weeks. I shrugged him off with an excuse, but it was enough of a speed bump to get me to reconsider it. Went home that night and shared my inner turmoil with my wife. Began counseling/treatment the next day and, while it hasn't always been easy, I haven't been back to that darkest of places since.