Exhausted by crush :( I'm so sick of this

It's been eight months now and I'm just so tired of thinking about her. I don't have anyone I can easily tell about liking her so I've kept it to myself and I know that's made it worse. I used to talk to her almost every day, but we didn't see each other all summer and then we were put in different classes so I still don't really see that much of her, which I though would make her easier to get over, but it's been four months since then and it's still as strong as ever.

I thought, for a week or two, that I was moving on. I could go ten minutes after waking up without thinking about her, and when I did it just felt like it was out of habit. But then she contacted me and asked me to her Halloween party - which made me think that I must be in some way significant to her, if we could go weeks and weeks with so little contact, but for me to still be on her mind enough for her to think to ask me? And then it all came crashing down again. I see her once a week at our college feminist group meetings, but it's not really a place where you can chat, and she's busy being intelligent and amazing while I say very little. I have depression and anxiety, so I always think people dislike me anyway, and I never know how to act around her. I know my issues all feed into each other and I'm seeing a therapist at some point, but I'm on an eighteen-week waiting list.

Everything reminds me of her. I feel so sad walking into the classroom I first met her in now she's not there any more. I miss hearing her say my name. I almost miss how anxious I felt talking to her. I just miss her.

The worst bit is, it's not all fucked up just yet. I'm going to her house for a party soon. There's still potential for us to just be friends. But it won't happen because I'm boring and don't know how to act, while she knows so many people and I must be so insignificant. I wish I wasn't so dramatic, but she's only my second crush, really - the first one I had was built more upon what I thought him to be, and once I'd spend some time around him I was over it. But despite knowing her flaws, I'm still obsessed with her. It's unhealthy and I'm ashamed of it. But I don't know how to get over her.

Sorry for the self pity I'm just so tired and embarrassed by it at this point. How long do crushes usually last for you?

Edit: I should add that she too is bisexual, and probably knows I am too, so that's not really an issue. Before I liked her, I was pretty sure she liked me - but I don't even know what reality is at this point.

Thanks.