When I think about love, I think not only of my children, of my mother, of my brother, of my romantic loves, but also about my best friend. Her name is Caroline and, in the non-romantic sense of the word, she was my first true love.

Over our 44 years of friendship, we went through everything together: school, work, marriage, children and divorce. Our friendship became so tight, our lives so intertwined, that we were like sisters - only without the issues that family so often brings.

We knew each other inside out - and through her I learnt the true meaning of unconditional love. As I have lurched through life, even when I couldn't pick up the phone to call her, I knew what she would say.

I could always feel her, leaning over my shoulder, shouting advice, reprimands, warnings and love in my ear. She never whispered, not even at the end of her young life, which came - heartbreakingly - just over a year ago from breast cancer.

Her death was the final hurdle we had to overcome. To share our true, uncomplicated love was wondrous, but to be without her has been a truly lonely and painful journey.

Through her I have discovered the real power of friendship and perhaps only in her death have I realised just how much a part of me she was, how much of myself I have lost without her.

For - and I believe many women experience this - I found that, in some ways, the closest relationship I had in my life was not with my husband, but with my best female friend.

It is not that I didn't love my partner, because of course I did deeply, but the bond and understanding I had with Caroline - like the closeness other women share with their best friends - was utterly unique.