I agree with Angela.
You find yourself in a predicament, but I think you know exactly what you need to do.
You say your father doesn't want you to spend money and that you should save it, and you should do just that. I'd go to a bank, especially because you are over 18, and get a second account that you can't draw on without giving signed id at the teller. Work out a way to direct deposit only 2/3 your money into your regular account and 1/3 into the savings account, then tell your father you had to take a pay cut. If he's going to lie and manipulate you, I don't see why you can't treat him exactly the same.
The other way is to confront your dad strongly with lots of confidence. This is by far the hard method because it will take a lot of courage. It's a case of laying the cards down on the table, and if he buts in tell him to shut the **** up. You may need to use those words for emphasis. Outline what you think of him, what your plans are for your future, and how he fits into them. Describe the impact he is having on your life. Even thank him and be grateful for all that he has given you of his time and money, but also be firm that it is by no means an obligation. If he really pushes it, use the son card - "How can you say you are my dad if you rip me off like this, what kind of father would blackmail his son? I'm not a ****ing paycheck for you." Still feel free to give him money, but control how much it is, don't let him control that part of your life.
I'd take the second route, only because I've done it once with my mum, and while it's not the same relationship, I'd say it's better. We respect and love each other now rather than the twisted obligation thing that happens.
They are only two possibilities though. You alread know what you need to do, you are just scared of doing it. Bring out your courage and go for it.