My mother also used this term "bent over backwards."

I think it means that they were trying very hard to cope. (most likely depressed themselves and unable to cope with the burden of cubs)

Their parenting was abusive and they could not cope with the cubs they failed to teach proper emotional intelligence too. The truth is they were lacking it and so they could not pass it on, like in healthy families.

I am not sure why we had to be blamed so much

Love and respect to you and all