100% Confident 50% of the Time

Monday morning, around 7am. I've just read over the chapters I wrote yesterday. They're brilliant. I visualise myself chatting to Oprah about the book that changed the world. The publisher that finds me is one lucky bugger. I've always known this was inside me, it's been there my whole life, waiting until I was older and wise enough to create it. 
Monday afternoon, around lunchtime. I'm a fraud, an untalented fool; this whole book is nonsense. I'm fifty four. If I haven't managed to do it yet, I'll never do it. There's a reason for everything. I visualise the rejection letters and my cheeks burn with shame. I will definitely be eating bread for lunch. 

I believe this is what makes me a writer: I'm one hundred percent confident about fifty percent of the time. What is it going to take to get me to finish this book? It's like the universe - ever expanding and I feel like it's been in creation since the beginning of time. There's an online community of writers I dip in and out of but won't participate in their chats because:
a) Their young adult fantasy book ideas sound obvious and immature.
b) Their young adult fantasy book ideas sound very like mine. 
c) They haven't attained the life experiences I have, so we can have nothing in common.
d) They are all younger than me, and most of them have already finished their fantasy novels.
I wish it were easy to slap myself across the face. 

The thing is, the book is sort of writing itself. It started life as a twenty minute play for young teenage drama students, all of whom had contributed to it by way of inspiring me. The hero wasn't even an original character; he was a twelve year old Spanish boy who started class when we were already weeks into rehearsals. I wrote his part hastily, a character without any dimension, who carries the bags of two old women in a desert (these two evolving out of my disappointment with my older youth theatre who had rejected a Beckett play - they thought it was absurd *sigh*). Because he was struggling a little with English, his lines were written simply. I told him that all ideas were welcome, and to speak up if he wanted to add something to his character. He nodded his head and said,
"Can I have a pig?" 
I asked if anyone happened to have a toy pig and it turned out someone did, and so, with no explanation of any kind, his character carried around a pig as well as the bags.

In my novel, he is a delightful innocent boy, the son of a pig farmer and just ten per cent less intelligent than his teenage sweetheart would like. The book, as I mentioned, is expanding at an alarming rate - I already know it's part of a trilogy - and the story is almost entirely different from the original play. The characters bully me, demanding back stories and layers of depth. What upsets me is that it was a very funny play, but the book is getting darker every day. Don't get me wrong, the ideas that come to me are exciting, but I wonder if the end will ever be nigh? One time, I had written over 70,000 words. I ripped that to half during a difficult bout of non-confidence but I think it was the right thing to do. If I don't cringe the next day, it stays. 

The boy - I called him Jones in the play, because he carried the bags you see, and I've kept the name. I smile when I write his story; when I realised where his arc would end, I almost cried with the warm feeling it gave me inside. But I've said too much already, and I'm assuming you will want to read the book. When it's written. To date, I've written 41,187 words that I can stand over. I shall have many more yet.