The other day, Mom wrote that her "heart was heavy" for recognizing another change in Lyn but she knew it was going to be a good day because Lyn was happy. The two emotions conveyed by her thought have been sticking with me a bit.
There seems to be no word in English to properly convey these conflicting emotions. The word "ambivalence" doesn't seem to do it justice. Ambivalence is the "coexistence of positive and negative feelings...drawing (you) in opposite directions." It seems to lack the weight and depth of the heavy heart. Perhaps we've come too far from the original meanings of ambivalence because it seems more closely related to apathy than what I sense from Mom.
Perhaps we can be so bold as to borrow a word from another language? Does "saudade" apply here? Saudade is a Portuguese word with no direct English translation. Saudade conveys a deep sense of longing for that which is lost. It is nostalgia wrapped in pleasant yearning. While saudade is typically thought to be felt to a lost lover or homeland, I think it may apply here to a woman who is watching her child become lost, who remembers with fondness and joy the child who once was and who recognizes the pain resident in the future.