You're just about right, both her husband and daughter are killed. And then she deals with it. But I have to agree the cinematography is amazing, especially the opening crash scene. I'm still trying to figure out what the fades to black are for within the same scene like pseydtonne mentioned.
For me, the "fades to black" seem to be a way to give us a view in to the internal dialog in Julie's mind. It's a dialog comprised of music. She doesn't need to take the possessions of her husband/child with her in order to visit them, or be near them. She only need close her eyes and hear the music. She is both recalling and composing during these moments. This isn't always a source of comfort for her. She wishes she could simply throw away the scores of music, burn them up and be done with it and have a clean start, but music exists beyond the written page and though she wishes to only live with the new emerging music, it's not that simple. -It's in her head and she is constantly reminded of that fact. -From the man playing the recorder outside her building, Olivier's insistence on resurrecting her husbands (her) final opus. These "fades to black" give us glimpses in to this struggle. That's my take on it.