Taking care of yourself during a difficult mental health spiral is hard work. Even the most basic of interactions or daily tasks (like getting dressed and feeding yourself) can feel insurmountable, and this deep exhaustion can lead to irritability and paranoia-based fights with even the closest of friends.
Ideally, people who know you well are able to parse the outbursts that are symptoms of mental illness from your actual personality and feelings. But even so, no friendship can last without mutual care, and dealing with mental illness doesn't serve as a shield against emotional responsibility.
He emphasized that regardless of what deep dark pit you find yourself in, it's still your responsibility to apologize to people for hurtful behavior, even if it's not intentional.