How can I get her to open up to me?

This girl just won't open up to me. Well, she has, just not in the way I want her to. Her name is Julie, and she doesn't suspect that I like her. I just started forming feelings for her a week or two back, and I always sit at her lunch table with all of her friends, which are ALL girls. Yes, I know, GIRLY, but they are awesome and pretty cool. She has a boyfriend named David. Her boyfriend is really perverted, and he did stuff with my ex that I just told her about last night. She said: "Ok thanks Nick" and that was the end of it. I'm surprised she didn't even get the slightest of mad at him today, and I didn't tell her that just to get her to break up with him, I said that because I don't want her getting herself into something she'll soon regret...and I'm really afraid he may force her to do something. But today, I came to our table and it was PACKED. I said "Move it guys!" and then Julie said "Nick, over here! Sit right here." That really made me smile. Then her friend Maddie came and tried to sit between us but Julie didn't really want her to! I told her to sit somewhere else and she just sat down. Does this mean anything? I text her a little more than I should...I texted her for a while yesterday, and I texted her today and I think I bothered her because she was trying to do her homework. I told her I was really sorry...no text back. And she likes to send one-liners or one-word texts back to me, I hate that. I feel like I'm being annoying. I like her...a lot. I really don't want to screw it up. This feels a lot different than most girls I like. How do I get her to open up? Should I sit somewhere different at lunch? Get her to like me? Any tips/advice? NO WEBSITES. Just personal experience please and thank you! If this helps, I'm 15 and she's 14. Her boyfriend is...14 I think? Thanks in advance! :)