Nobody is sure of the cause of her making the decision to end her own life as yet, the Hospital and St James palace have both issued statements saying that she was supported and not subject to any disciplinary action as a result of being duped.
If the two broadcasters responsible are feeling bad about their actions just now whether they were an influence in the decision that ultimately led to this death or not then you could class them as having at least some sense of human responsibility.
Sometimes tragedy is just that, it doesn't lessen because there may be a cause to point fingers at. There's also a point to be learned as to whether she'd still be alive today without the action of those radio presenters.
What we do does have an impact and it can be the unseen last straw that would bring about a decision for someone to take their own life. Sometimes we say things expressly to make an impression, an impact or cause influence, we can't then say we haven't played a part and she died because she's was just a flake.
I agree totally with the OP's title, it's very, very sad.