I loved this the first time I read it, especially the dialogue. Now, after reading all of your 15Pairings fics, I think this is my favorite. I don't think Tomoyo is so terribly out of character; personally, I much prefer to see her admitting to anger and hurt rather than being so completely self-sacrificing and "pure" in her feelings for Sakura.
The spell with the rain, at the end - it's not just that it's a great spell and image to use, but also the way you describe it that makes it work so perfectly here.
I always like seeing inside another writer's mind, too, so I love that you posted this version.