Did Christine mean what she sinabi in Past the Point of No Return or was she just trying to convince the Phantom that she did?

Personally, I think she was rather trying to convince the Phantom that she really meant what she was saying.

Here's why.

Remember, when the Phantom comes in, she looks above her shoulder to see him, and looks shocked. Then she turns back, closes her eyes, and you can see all the pression she has. She knows she'll have to do it, so the Phantom won't be ever after her. But it's hard for her to betray him (remember "Twisted Every Way"). But I think that she realizes that finally, in order for her to become an adult, she'll have to take responsibilities (because throughout the whole movie, Christine has been totally childish and irresponsible).

So, she plays the game, and at a certain moment, while the Phantom has his head near her neck, you can see that her eyes are wide open (she's not swooning at all) as if she's determined. Then... she rips the mask, to ipakita everyone that the Phantom is there.

To me, if she really meant what she was saying, the mask would have stayed at his place.