So square:

She kept presenting to the emergency room because she knew she was a danger to herself and others

With:

The psychiatrist testified that Clancy never told her about manic episodes, a criterion for bipolar diagnoses, nor about hearing voices or having other signs of psychosis.

Clancy at times said she was “close” to feeling suicidal, hopeless or like she was going to die, Tufts recalled. But she said Clancy denied having a plan to take her own life or harm anyone else and never revealed — as the defense says she did to her husband — that she had thoughts about harming the children.

And the fact she seemingly told nobody else she felt like she was a danger to others.

Where did she tell anyone about this? Not that the hospital didn't still have a duty to care for and admit her if she had thoughts of self-harm, but it sure seems like she intentionally lied by omission.

OK That's absolutely her being responsible, and the healthcare system failing her.
That is something to take into consideration, not the insanity by itself.