I know exactly how you feel. My dad is a completely useless excuse for a human being. My mom, who was an amazing person (and whose only crime was falling in love with a total *******), died when I was 7. From then on, my sister and I were raised by our dad, who was verbally abusive, always had an excuse not to work, used marijuana (not so bad) and cocaine (kind of a serious issue!), and (most relevant to this site), fed us nothing but junk food.
My sister still lives with him in BC, but she's planning on moving as soon as she graduates from high school after next year. I moved immediately after grad to the other side of the country, and I rarely talk to him. From what I hear, he hasn't had a job in about 2 years now, because he's too "sick".
It's good that you're going to therapy to deal with your emotional issues. I would probably consider it if I could afford it. However, I've healed for the most part, and life is looking pretty good these days. What I've learned is there comes a point where you have to take action, and that means taking responsibility for your own happiness. For many years, I used the victim excuse. I made myself believe that it was ok to be miserable and overweight because of "all that I had been through." But eventually I clued in; Yeah, life can suck sometimes, but it's up to me to make it better and to make sure that I enjoy every second of it!
I hope that you can find the healing that you need, and if you ever need someone to talk to, I'm always willing to lend an ear or a shoulder to cry on