An awkward issue with my bisexual friend...?

A friend of mine is trying to guilt me back into being friends with her after she tried to touch me in my sleep. This is while she was staying over at my house (she has financial problems, so she doesn't have a stable place where to live). I'm 17 (18 in 3 months) and she's going to be 18 in a couple weeks. We don't go to the same school, but she talks to me a lot. She has always been very clingy and needy, which can get annoying at times. But I've remained friends with her because she says I'm the only person she can truly trust, and I feel kind of bad for her. She is very emotional, and gets depressed easily.

As I said before, this happened while she was staying at my house. This was the first time she ever slept over (usually she sleeps in hotel rooms, or in the houses of her other friends, but since her dad's car broke down not too far from our house, he asked if she could spend the night and my parents agreed).

At night while I was trying to sleep, she started making awkward advances on me, and telling me to kiss her and get on top of her. She didn't "rape" me, but if I had not rejected her things would have probably ended up badly (well, for me anyway). She said she has a crush on me, so when I refused and reminded her that I'm straight, she started crying. I tried to tell this to her as nicely as possible (which is probably a mistake, since I wasn't assertive enough with her). She has told me that she likes me in the past, but I thought she had gotten over her crush already. Plus, she has an online girlfriend (though she has cheated on this gf in the past with another girl).

Now, she is offended that I feel like I need time away from her. She says things like "Why are you upset?" and "Yeah, I guess what I did was a mistake..." like she doesn't understand what she did to me. I'm not even trying to be rude to her. If she was a guy with a gf I still would have rejected her because it's not right to cheat, plus I do not feel attracted to her at all... and if a guy was trying to make advances on me, and I did not feel attracted to him, I would tell him to stop, especially if he had a gf and was making me feel uncomfortable.

She also tells me that she's only concentrating on her online gf now, and that she's gotten over her crush on me by focusing on her love for her gf. She is constantly calling me up and txting me, even though I don't really want to deal with her.

The day after this happened, her cousin txted my number (which she gave to him, since I wasn't answering her txts... I was at a family gathering). In the txt, her cousin said that my friend wanted to talk to me. When I called her number up, she asked me if she was still sleeping over the next day. My answer to her was that I think I need some space to her (and I said this to her as gently as I could).

It's been about 5 days since the sleepover. Today she called me 4 times in a row, and when I finally answered, I told her that I needed some more time apart from her before I could forgive and forget (which is what I've been telling her all along). But she's still being persistent, and telling me that she doesn't understand why I'd feel awkward around her.

As I said before, I'm dealing with her the same way as I would deal with anybody else. Although I'm straight, I have friends of all sexualities who I spend time with on a regular basis, but NONE of them have ever tried to do something like this to me.

Would you go back to being friends with this girl? And do any of you have advice on how to deal with her? Thanks.