Please! Someone help me with this movie!?

Ok. So when I was probably 7 or 8 or somewhere around that age group I remember waking up at like 4 in the morning and the TV was on and there was a movie on (I'm thinking it was made in like the late 90's or early 2000's) And it was a movie about two sisters (One was a blonde and one was a brunette) And the blonde commited suicide or something or fell off a cliff or drowned..or the brunette sister pushed her off a cliff into the ocean and where she fell, there were rocks and she cracked her head open on the rocks and the water washed her away so there was no evidence of the body and the brunette sister was being haunted by the blonde. And at some points of the movie, the blonde would poses the brunette's body and it was just a very confusing movie. And the mom i think was like blaming the brunette for her sister's death or there was something about the mom being a.....not nice and there was also something about the brunette having a split personality or something. It was just a very twisty-turny movie. If anyone has any idea of what movie this is, PLEASE PLEASE PLEASE let me know! I've been trying to find the name for years so please let me know if you even have the slightest idea. And this may not even be accurate info about the movie, but it's what i remember. Please help!