I think it was a bit of both, Jane. She was protective of them around other people, but the lethargy induced by the Haloperidol caused her to oversleep in the mornings, which meant the twins had to fend for themselves and were late to school for a period.
Her mental health was shattered.
All descriptions of her are of being " scatty, unable to maintain work, dizzy, " etc.
How can a lady have confidence when her nearest and dearest don't think much about her in terms of practical capabilities? Her relationship with Nevill was warm and probably was the most comforting point. Jeremy and June were not warm to her.
She came from a family of practical strong headed women. June, AE PB, MS. She wasn't in the same mould of them. And I believe they never failed ( in particular June or course ) to remind her or her shortcomings and how " she was expected to be" ( which of course she wasn't in reality)
Her confidence would have been at the lowest from adolescence till death. Meeting Colin and having the boys the soul joy of her troubled life.