BlueRose
So...how to proceed?
1) Since it is your parents' house and they want to keep him there, then there is nothing you can do about that. It sounds like he has a sweet deal --- doesn't have to pay rent only kicks in some money towards bills. IMO, your parents aren't doing him a favor in the sense that this type of arrangement will stunt his emotional growth. Why should he ever grow up and get his own apartment with this sweet deal in place?
So...
2) Sorry to say, it looks like you'll have to be the one to leave. Obviously, it won't be easy. The college you are going to --- does it have dorms or is it a commuter school? If it is the former, then look into some sort of grant or financial aid that will allow you to live on campus. If it is a commuter school, you will have to continue to live at home (if you insist on being a full-time student) and save your money so when you complete your education, you can move out.
3) As far as your Dad is concerned --- you can still visit your parents and lend them a hand. That's what families do for each other. As long as it doesn't take so much of your time that you feel you're spending every free moment helping them.
4) Breaking up with the BF --- I'm assuming you can have your own bedroom in the house? If so, you should be in it already. This will put some distance between you and him. When you're ready to move out, then just let him and your parents know that you --- and you alone --- are moving out. If BF feels bad and tries to lay a guilt trip on you, don't fall for it. Of course, breaking up is never easy no matter what the circumstances but it's better than being tied to a BF out of guilt. If he doesn't want an amicable break-up on friendly terms, there is nothing you can do about his feelings.
Finally, here's a thought --- can you go to school part-time and work full-time? That way you can get out of the house sooner. My husband took 9 years to get his degree. Some semesters he went to school full-time and worked part-time and others he worked full-time and went to school part-time. When he was a full-time student, he took advantage of loans (and the GI bill, which I realize you don't qualify for). As I said before, look for grants, loans and scholarships --- if you haven't already.