Here's a few points you might want to consider:
First, I would suggest that you first find a stress-free (part-time) job (any job). I believe that the feeling of accomplishment you will get by making your way through life like everyone else would be very beneficial to you. Once you establish a certain equilibrium in your life, then you can start changing it in small ways to make it better. From what I can tell, what you really lack is equilibrium.
Second, have you considered private tutoring? It pays pretty well, and usually your students are much more interested in what you're teaching than the average HS students. An even more rewarding case would be tutoring undergraduate students. These guys are often much more interesting to instruct. It would also solidify your understanding of the subjects if you ever decide to complete that PhD.
Third, lay out a plan. You say that you want to be a professor, I say go for it. You don't have to (or can't) do it hard (like most of us), so do it smart (you say you're a pretty smart guy

). If the problem is that you can't handle the pressure of a PhD, then do it more slowly. Get a part time job to sustain yourself and take your time doing it, just for your own satisfaction. If abstract mathematics is too hard for you right now, consider something less taxing on your mind, for instance some engineering application (highly depends on the case, but you get my drift). Once you have your degree in some years, it's possible that you can replace your part-time job with something you enjoy much more. Again, lay out a plan. Planning is much more effective than medication in order to reduce stress.
Other things you could do could involve working at home. My first suggestion would have been to start your own business, maybe writing software or something similar (if you have programming skills), but this is a very stressful way of living. Instead, how about writing apps and selling them as a way to complement your income? As long as you don't have a boss, deadlines, and having to worry about how to survive, I can imagine one can work in a pretty stress-free fashion

. If it takes off at some point, you could do it full time.
Also, I believe working long and hard in academia is overrated. I spent the last 1.5 years working ~12 hours a day and I found that my brain simply stopped working effectively very early in the process. I started forgetting things and taking far too long to do math, which simply lead to working even more. I now try to work a healthy 7-8 hours a day and it works much better.
My last advice for you would be not to be afraid of life. You suffered a great loss, but it's going to be the end of your dreams only if you let it. Many of us are stuck in low-paying jobs that we don't fully enjoy. But by doing so, we also make our way through life until something better comes along, making ourselves more employable in the process. Trust me, as much as you would dislike "waited tables for 2 years" or "student tutor for 2 years" in your CV, it still beats the hell out of "unemployed for 2 years".
So lay out a plan to make your dreams happen (even adjust them accordingly), take it easy, and try to enjoy life as much as you can. You may get your PhD at 37 instead of 27, but you can still get it. We are young, and we tend to think that when something very bad happens it is the end of the world, but we are wrong. There is a full life to be lived, and we must each live it with what we've got. It is really unfortunate that you have such difficulties, but try to take comfort in the fact that you are not alone. Everyone has their cross to carry. I knew a guy doing his PhD. He was really great at it, but then his father died and he had to give it all up to run the family business and support his 4 brothers and sisters.
Bottom-line, we always tend to want something ideal out of life, but please take comfort in the fact that most people really have trouble realising their dreams in the end
