SERIOUS CONSTRUCTIVE POST
Thought I'd clarify.
You can't see dating as a "buying" and "selling" thing. You were prepared. You THOUGHT she was going to be your girlfriend. You put too much money on a first date anyway, if it was that serious. It would have probably scared her off if she even had feelings for you, not to mention the love bit, but I don't think you said "i love you" though... at least you hadn't said so.
Take this as a lesson. First dates dont have to REQUIRE money. Take her to the gardens, etc. Even movies or ice skating, it costs about $20-30 MAX. You were too sure, so let this be past-experience, and I guess now you can learn from your mistakes and take the bar down a little.
This girl does sound a bit weird, you can do better. She should have been firm and just said "no", and KEPT saying no, and stay with it by explaining to you in honesty: I don't have feelings for you, I just don't see you that way, I'm not interested etc.
SO yeah, take it as a lesson, and move on. Don't be upset. You've got another few decades to wonderfully treat a decent girlfriend.
EDIT: didn't read that "married" bit.... dude...