SOLVED. YA Fantasy Book, recent, maybe a trilogy about angels [s]

[Mary]

Sooooo, some months/years ago I was in a bookstore and I opened the last book of a series. I can't remember the name of the book or the series itself, but I read the last pages. I think is about angels, the cover might be black. Anyways what I remember about the end *SPOILERS AHEAD*

The last epic fight against evil happens, and the girl, the leader character, dies sacrificing herself; I think this fight happened in another dimension. Something like a portal/door closing, I'm not sure about that. But I'm sure that she doesn't come back. (It just occurred to me, and I don't know if this is about the same book or it's another one and I'm confusing the books, but in the first book there's an accident and the girl was supposed to be dead then, but she didn't for some reason). So, in the end, the very last pages, there's this kid that I assume is her brother and a guy who I think was her love interest. They are talking on the porch about how they will miss her, and the guy finds a coin in the ground, because of this coin he knows that she is with them somehow....

[Mary]

A friend of mine just told me the book serie is Kissed by an Angel!!