Losing someone

I just watched an episode of One Tree Hill. Hayley and her sister lost their mother. The whole episode was filled with emotions and was so sad. I was crying. How can you not when someone is losing someone? Even if it´s just in a movie or TV show. It´s still real.
If I lost my mother, my whole world would crash. If I lost my dad or my sister my hole world would crash. I would hide in a dark corner and probably never come out. I would dig this deep black hole and stay there.
My sister is such a big part of me I don´t know what I would do if I lost her. A big part of me would be lost and I would feel so alone. Same if I lost my parents. We have a great relationship and I love them very much. The thought of losing them...