You asked a man to choose between you and his own child? And how did that work out for you?
Ultimatums are bad enough, but to try to force a father to give up his own child for you isn't just dumb, it's incredibly selfish, too. I would have put you out the door so fast, your head would spin for weeks afterward. I don't care how problematic the girl is; she's a child and you are an adult. You should be the bigger person. Of course she's going to rebel against sharing her father with you. She's 14!
Yes, you should end the relationship--if your boyfriend hasn't already. You don't have the maturity required to date a man with children. A mature woman would be working to find common ground and coexist instead of trying to make a man kick his own daughter to the curb.
Grow up, honey. Seriously.