The Ending? (Spoiler)

Hello :)
I watched this movie today and found it great. The only thing which wasn't clear to me was the ending. The dead rat in the ice which begins to melt means that the feelings of the family members stop being frozen, am I right with that? I saw hope for the parents, it was clear to me from the moment when Brigitte intoduced her new lover to her husband. She and Henrik were apparently still in love with each other. But what happened to Lars, their son? Did his breaking in the lake had a special meaning? Did he survive? I couldn't really figure that out...
But the movie was very special and really wonderful :)
Sarah