The crossfade of the apartment before the last scene.

Right after Séverine leaves the Hospital with her friend, after the doctors tell her the bad news about Pierre, we see her both walking outside the Hospital, then cut to a shot from outside of the apartment where Séverine and Pierre live.
But then the apartment begins to crossfade with something that seems like a forest, maybe the one where her fantasies took place. After that notorious crossfade, the last scene begins.

What are your interpretations of that crossfade? I think it means fantasy and reality coming to terms, where both worlds collide.

That shot alone, to me implies that it wasn't all a fantasy. That she indeed, live a double life which ends with her husband getting shot, blind, etc,