That really stinks that your dad ended up doing that to you. Having your dad go back on something that they said they would do always really really sucks. It's why I no longer pay for something on my CC for my dad if he promises to pay me back for it. Because it never happens for the full price of what was paid, let alone intrest. My dad still owes me for $300 that he borrowed from me to pay for our dogs surgery 5 months ago. The dog had to be put down since then, sadly.
I worked a crappy job my first semester freshman year, about 32 hours or more depending a week. 4x8hour shifts a week, ontop of 15 credit hours. I did okay, but ended up withdrawing from one of the classes because I couldn't keep up with 5 of them, putting me down to 12 credits. I quit the job for the second semester and my dad was picking up a little slack, but I had saved up money to pay for gas throughout the semester. I ended up doing worse the second semester because I didn't feel the need to manage my time better, so I spent alot of it slacking off.
Whatever happens, just be sure you dont start slacking off. Good luck to ya OP.