The thing that always broke me when I tried to quite the pills was the depression. The aching was pretty bad but my god that feeling... I totally get where your coming from. For me, I didn't get stoned and nod off all day. When I had my pills, I always got everything done. I had the motivation to do it all. Without them I didn't even want to get out of bed. Unfortunately, I agree with junkDNA...its incredibly hard to get off them even when you don't have constant access to them.
Maybe talk to your dad. Set something up with a pharmacy where he only gets small amounts...join a drug rehab.
To be honest with you, I couldn't do it. I'm on methadone and although it keeps me away from that life, it is just trading in one crutch for another.
Don't be so hard on yourself, you are dealing with some pretty heavy stress, and it sounds like your alone. Maybe that's why your dad hasn't said anything, maybe he feels bad about what you've had to deal with alone. If you ever need to talk, I'm here. Hang in there.