Well, I just spent the past hour writing about Batman and drinking wine, which tells you how good my advice is, but I hope you'll listen to me. You know I care. So here's my addition to the advice pile.
Tell everyone everything. Acknowledgment makes everything better. Apprehension makes everything worse.
You are not responsible for your friend killing herself. Was there something, somehow, that you could possibly have done to prevent it? In another place and time, just maybe. But lived your life in the way that you could only be expected to, and it happened anyway. By the sound of it, you were a great friend to her too. All other implications aside, you two wouldn't have been so close if you were in any way the cause of her terminal sadness. It was not your fault. I know all too well how hard that is to believe, but I assure you, it was not your fault.
And as for the attraction, just talk about it, especially if it's the kind of thing that you know can't happen. Well, I say that, but that didn't exactly work out for me. On second thought, try to figure out why you're attracted. Hell, tell us - we can't hurt anything, and just hearing someone else's perspective might shake it out of your head.
And the friend, well, that's life. And sometimes you don't feel so helpful. You just have to do whatever you can.
You know we're always here and we like you. What little that matters sure, shadows in a cave and all that. But I'd like to think we're better than nothing, and we are your friends.