The Dark Sea Calls by Michaela Haze

With the death of the dowager Mer-queen on her hands, Maeve knows that if she ever wishes to return to the Twilight Lake, she will be killed.
An enemy of both sides of a war.
Running from the only home she has ever known, Maeve Cruinn finds herself washed on the shore of the Siren Cove, a place that other fae fear to tread.
When the Siren Queen and her son take her under their wings, Maeve finds that the truth of the Twilight Lake and her mother’s death are darker than she could have ever known.
It seems that the Gods are not on her side when Maeve finds she must return to the lake.
The four princelings want Maeve back,
But is it to pay for her crimes?
Or is there something they’re not telling her?