Depression is a major illness in and of itself -- and works at killing someone through the mind-body connection -- it is the root of all sorts of nerve disorders, all sorts of headaches, pain etc.If they had showed that ahe had heart problems or cancer ... then people would have thought that she fell ill because of genetic problems and the state of her daughter was incidental...so they showed that she was dying of depression... so that it would be very clear to individuals that she was dying specifically because of guilt.Depression is a serious illness, because many people lose the will to live -- it is called "ichcha tyaag" of one's life -- not suicide, but just generally one feels that one has no goals to look forward to or to live for, and basically people sort of mentally shut down and this in turn leads to a physical shut down.I dont know if you have heard of cases where a 65 year old woman dies, then within two weeks her 66 year old husband dies of mysterious causes -- there is no real physical cause, but just that the husband lost the will to live after his wife's death -- or mothers who die soon after their child may have passed away.