I was going to say I appreciate your sincere concern for your father. There's nothing wrong with living at home- if you like being around your dad and it makes more financial sense to do. My aunt didn't move out til she was thirty, but she's married now, with a kid and a high-flying entrepreneur.
Anyway, I can't believe she's basically blackmailing you into sharing your stash with her whilst she's being such a golddigga, according to your account if her. If this is true, she's bitch, but if you still think moving out before you've had a chance to settle in to college (changing address can also affect what government funding you may be eligible to receive) put it to your dad that it's either you or her. Perhaps it will force him to finally examine her under a negative light and see her for what she really is. You are his son and it sounds like you care for him alot, he should be able to see that and side with you on this.
Whether or not this went in one ear and out the other, good luck anyways...