Wow, this is in some ways like looking in a mirror. As most of the folks here know, I've also overcome a drug addiction. It got so bad, I left the country because my willpower wasn't enough. I have never had a father, my grandparents were always there for me and my mother went through hell and high waters to give me the best she could, despite every month having to count the pennies.
What I'll say is this:
This isn't the time for you to be down about stuff like this. This is an opportunity. It's a time for you to lose the shackles you have, and start living your own life. It's always shit to lose people who you can depend on, but it does teach you to fend for yourself and become a stronger person.
Your breakup with your girlfriend might have been exactly what you need. If you were in a stale relationship, there's really no point staying. See this as an opportunity to find someone new, someone exciting, someone you want to buy flowers for and spend time with. Until then, use this time to think about your priorities in life. It sounds to me like you're in a rut and need a change. Sometimes changing one aspect of your life is enough, sometimes it's better to change as much as you can. In this case, your relationship was stale, your job is stale, you're potentially losing some loved ones (sorry if that came out wrong), so it's time for you to throw your life up in the air and see how you land.
Career wise, a change of environment can make a massive difference. I changed job recently having spent 4 years working for the same company. I do pretty much exactly the same thing, except for a different firm. I'm loving it. I work crazy hours, 12 of them a day, but I also get tons of time off. I make a decent living, and I'm generally happy with my position. Even if you're doing the same thing in a different firm, a change of environment can make a huge change.
I found a person who is just as fucked up as me and we got married. She became my new rock. We're now married and living happily. She keeps me on the straight and narrow, and it sounds to me like this is what you need too. Focus first on finding a job which will make you happy again. This will in turn boost your confidence, which will help when looking at girls. When you lack confidence, any old girl will do, but if you're feeling good about yourself, odds are you'll look a bit deeper and find a woman who suits you better.
Don't see this change as a bad thing. You're young, you have a few years left in you, but just ask yourself this: what are you going to do to get the most out of them?