The girl that I like learned about my feelings from Facebook messages and is sending me mixed signals

Ok, so this is a bit of a long story so I'll try to cut it down. Basically, I met my friend (let's call her Jane) about a year ago. We're both in high school. I happen to be bisexual, I came out to her and the rest of my friends last March. It was around then when I began to have feelings for her. My best friends have always thought that she liked me back. She gives off a definite lesbian vibe, and they've suspected ever since they were kids. Anyway, my best friend (let's call her Pearl) and I are so close our minds are practically connected. We've talked about my crush on Jane for the entire time I've liked her over Facebook message. I confided everything I thought about Jane to Pearl in those messages and we tried to figure out how Jane felt about me. We didn't talk about much else over Facebook because those things were saved for phone calls and talks in person. Last weekend, Jane and Pearl were having a sleepover. Pearl left her Facebook account open and Jane, being a bit of a troublemaker, began to read the messages exchanged between Pearl and I. She was, in a word, shocked. I do know, though, that Jane has suspected that I liked her before. That same night, Jane came out as bisexual. She told me the next day about both the messages and the fact that she came out. She has a personality in which she tends to like to avoid serious topics. She has repeatedly told me that it's fine and that she's totally comfortable and that I shouldn't worry. She's even said that it's sort of funny. Lately, she's been even teasing me a bit about it. But, when we began talking about it, ironically over Facebook message, when I said that I understand that she doesn't feel the same way about me she said that I didn't know that. I asked what she meant and she replied that she's in sort of middle ground with this. I don't know if this means that she likes me or not and it's confusing the heck out of me! Lately, I've felt as if she's been touching me a lot more than usual and maybe even flirting with me. I can't be sure though, but I've even caught her staring at me a few times. She compliments my eyes and appearance as well. She told her lesbian friend about the situation, but I don't know exactly what they talked about. Anyway, I think that her friend was trying to make her look good in front of me but I cannot be sure. Now, I sort of want to ask her out. Though, I, having no dating experience whatsoever, don't know how. We've always been friends and I'm not sure if she wants it to be more or not. Especially after she's been so kind about this whole issue, I would've been freaked out of my mind after reading someone talk about me the way I spoke of her to Pearl. I don't want to ruin our friendship and I don't want to make her feel uncomfortable. I feel as if the only thing keeping us friends is the understanding that I'm not pushing a relationship right now. How can I ask her out? Should I even ask her out? I have no idea what to do without messing up our friendship which I really value.