Outsider's perspective

So... I'm driving myself mad and could really do with some (more) outsider perspective.

I never really had any long-term relationships. I never thought I was the type. Friends with benefits, causal open relationships were 'my thing'.

That's how I started off things with this woman. Fantastic sex, great connection, great friends. Untill I fell in love. Bad.

We made a complete ****ing mess of things. She's going through a shitty period in her life and, lacking close friends at the moment, really came to depend on me for support. Me, being madly in love, refused to see the rather obvious, that she she didn't feel the same way. We both knew, talked about a few times, went on and off a couple of times, and now, finally, decided to take a "time out".

Being the idiot that I am, I assured her that I would be there for her should she ever need me. Told her we could remain friends, and that I just needed some time. After all, I've remained friends with most of the women I've dated. Now, however, I hope she doesn't take me up on that offer because I simply can't live up to the promise of being a proper friend to her. Atleast, not in the foreseeable future. I really can't be her around her, since leaving the door open, even a little bit, means I'll be driving myself crazy.

My problem is.. Should I tell her I can't be a friend to her anymore? Is there any chance she thinks I just need some time and then we can be friends again? I really don't trust my own judgement in this. I feel as though I owe her the truth, and that being honest now is better than putting myself (and her) through this again at a later time. I worry I may be unconscionably trying to hurt her by withdrawing myself so completely, hoping she'll turn to me for support, and maybe get another 'last time together' out of it. I've never been he manipulative type, but I find it impossible to clearly judge my motives at the moment.