It's funny,but I never perceived Sheila as a bitter person,even with her illness. She had had the twins and so was no longer worrying whether her earlier abortions had prevented her from becoming a mother,she had her Maida Vale flat with the bills paid..she was trying to learn more about religion to please her mother June,not the other way round.
If you're looking for the bitter personage in this story look no further than Jeremy. He was bitter at having been packed off to another strange environment at 8 years old,when he finally received a modicum of freedom he was bitter that he was rejected at his dream job as deep sea diver because his skull had been damaged due to June's neglect when he was a baby,he was bitter at the clause in Nevill's will which tied him to the farm during his father's lifetime,and he was bitter at the perceived preferential treatment Sheila was receiving at the hands of June,when the dividends of the caravan park went straight to Sheila,whereas Pamela Boutflour showered her income from the park on Jeremy's cousin,Ann Eaton.
Steve,,how do you know what was going on in Sheilas' mind.? Sheila was actually hospitalised for a few months while pregnant with the twins,,so she'd obviously suffered trauma there,,then post-natal depression which was then left to develop into something of a psychosis.
I have a good idea what she suffered afterwards,,as her mind would have been in turmoil,,,maybe blaming the twins on how she felt,,then Colin for giving her children. It wasn't long after the twins were born,that they divorced,,so that has to ring alarm bells about her delicate state of mind.
Against Sheila,Jeremy had a far more balanced outlook and didn't show any signs of violence or any of the other traits you get with young people,,but Sheilas' life was doomed from the start,,as in her teenage years,she was on a downward spiral.