Carl's eyes bulge, frightened by the expression on his mother's face. She sees this and smiles, but from the look in his eyes she knows he doesn't believe her. She begins to talk, not because she thinks it will help, but because she needs to get something out.
She wants to speak to her son.
She wants to explain to him, then and there, what is happening and how she feels. She wants to apologize for the implications. She knows the decisions she makes affect him as much as herself. She wants to tell him she feels young, as if she hasn't slept a day in her life, as if everything she ever knew has faded. She wants him to know that she loves him-now that she knows what is meant by this.
She will always love him, he will always be her son.