what chapter did edward say..... and so the lion fell in Amore with the lamb?

"So the lion fell in Amore with the lamb" is in chapter 13 on page 274 in the 4th paragraph.

en el capítulo CONFESIONES. Se encuantra en la página 280 :)

It's chapter 13, called "Confessions".
Edward says it on page 274, 11th line.

Here's the lista of Chapters, in case te need it:

[Preface]

First Sight, Open Book, Phenomenon, Invitations, Blood Type, Scary Stories, Nightmare, Port Angeles, Theory, Interrogations, Complications, Balancing, Confessions, Mind over Matter, The Cullens, Carlisle, The Game, The Hunt, Goodbyes, Impatience, Phone Call, Hide-And-Seek, The Angel, An Impasse, and..

Epilogue: An Occasion.

which page was it when edward detto the bella and so the lion falls in Amore with lamb