Clara squeezing her mother's nose as she lays dying in her bed

When I watched this scene, at first I thought it was just a fantasy that Clara was having where she had thoughts of wanting to end this agony of caring for her dying mother, etc. But she had just told her she loved her moments prior and after the mother dies, she climbs up onto the bed beside her and lays with her lovingly. It was made to look so real that I concluded she did in fact end her mother's life. Essentially, mercy killing her. Now I'm not so sure. It seems too impossible to believe she would truly take it into her hands to finally end her mother's life. Any thoughts on this?