So, this afternoon it took forever to get Mr Darcy to fall asleep for his nap. I finally managed it...and there was a loud knock on the front door. Cursing, I gathered up (the now-wide awake and crying) MrD, answered the door - and discovered that it was my book contracts being delivered.

OMG. OMG, OMG, OMG!

There are very few things that are worth waking Mr Darcy from a nap...but this was definitely one of them!

I thought I knew that this whole thing was real - I mean, the copyedits were pretty persuasive - but I just had no idea until now.

I'm so giddy, it's hard to think straight. But as I was dancing around the room with MrD and Maya, I suddenly started crying from sheer gratitude and relief.

This isn't just fulfilling my biggest dream ever since I was seven years old (almost 25 years ago). This is absolutely saving us.

I've talked before about how Kat by Moonlight (or whatever the official title will actually be!) was always the book of my heart, the book I wrote because I had to, because the characters were calling to me, even though I thought it was the commercially crazy choice of projects, and even though I truly believed that I could only ever sell dark, angsty adult books. I wrote it anyway, just for fun, just for myself.

But I haven't talked so much - at least, never in any public posts - about why. About what was going on in my life when I gave in and wrote Kat for love, against all my commercial instincts.

I got sick in 2005. Really sick. Sick for months, and no one knew why, although there were lots of different theories raised. Months passed. My day job gave me the option of either being cut down to half-time or being fired for being too sick for too long. I chose Option A, and our finances suffered. Eventually, though, in spring 2006, I got better. I thought I was over my Mystery Illness, and lo, there was much rejoicing. Then everything went wrong, in one smooth streak. Two relatives died. Our beloved dog Nika died of a long, horrific, painful illness that summer. I went into shock. And then, in November 2006, I got sick with the Mystery Illness again. And I just didn't get any better. In fact, I got worse, to the point where I couldn't even walk to the end of the block without shaking with muscle tremors, pinned to the couch and barely able to move for hours afterward.

Months went by. I finally found out - by accident, when the receptionist told me! - that my doctor had a new theory of what was wrong. And she was right. In February of 2007, my company paid to send me to an occupational therapist, who gave me the same diagnosis I got officially about a month later, from specialists in that illness: Myalgic Encephalomyalitis (ME), known in the US as Chronic Fatigue Syndrome (CFS).

I quit my job just before they could fire me. And I went into a really black hole of unhappiness.

A person who can't work in our society - who can't bring in an income - is a useless person, by unspoken definition. No, I take that back - it is spoken all the time, by every person and politician who complains about the "slackers" who live off benefits and "pretend" to be too sick to work.

I couldn't work. I couldn't bring in any income. Our finances got scarier and scarier. I felt like a completely worthless person, despite all of Patrick's love and support.

Writing Kat was what got me through it. I abandoned the serious, angsty adult novel I'd been trying to write. I wrote Kat for myself, despite all my panic - we were desperate for money, how could I write something I knew was too quirky and individual and personal to sell????? - because writing Kat kept me sane. Kat and her sisters made me laugh instead of cry, and in Kat's reckless courage and self-belief, I could let out all my frustrated desire to run and jump on horses and have adventures, even though I was physically trapped by my illness, forever lying on a couch. There were some days that I couldn't even stand up without Patrick's help. But I could write Kat's adventures, and I did, and they kept me going. I finished Kat, I started sending it around to agents, and as 2007 turned into 2008 and the sickness didn't get any better, I wrote the sequel against all common sense, because it was the only thing that could keep me going and keep me from despair about my illness, about our finances, about my value in society.

And now here's something else I've never publicly said before, because talking about money somehow feels just as shameful, in a different way, as talking about illness.

My wonderful, fabulous agent got the Kat trilogy a 6-figure advance.

When I first found out, on the phone last summer, first I screamed with joy and shock, and then, after I hung up, I cried. And today, looking at the contract, looking at the money that's going to come in and save us, and looking at my beautiful baby, who brought with him a near-total remission of the CFS after years of illness, I cried again, with amazement, with relief, with gratitude, and with the after-shocks of all those years of illness and financial and emotional terror.

We're going to be all right. I can go on walks with Patrick and Maya and MrDarcy now. I can be a real mother. I can visit schools and give talks to promote my books. And we can pay off my student loans, move into a bigger and healthier house, maybe even buy a house, which I never thought would be possible. I can contribute to my family, not just financially but in every way.

And it all comes down to Kat, the girl who wanted to save her sisters, and ended up saving me.

I am so grateful.