Feeling shame, guilt, contrition, or sadness may not be pleasant but these emotions aren’t “toxic”.  Shame, guilt and contrition help us learn from our mistakes and eventually move on. Sad thoughts allow us to appreciate the preciousness of what was lost and the preciousness of what is still here. Thoughts that amplify bad feelings aren’t necessarily dysfunctional – they may serve a useful purpose. Some unpleasant thoughts lead to breakthroughs; others become repetitive and reap diminishing returns. It’s not the quality of unpleasantness that counts; it’s the sense of whether the thought is valuable or useful in some way. We should be careful not to pre-judge a thought or emotional state just because it is unpleasant. Sometimes we have to bear with negative feelings and thoughts for a while. Sometimes dwelling feels right.

Of course, some of us are prone to unproductive rumination and so a heuristic to nip rumination in the bud may be useful, at least some times and for some topics. And using positive self-talk to counter habitual self-condemnation can also be a valid tool in the emotional regulation toolkit.  If we're stuck, we need tools to become unstuck.

But that's a different thing altogether from consideringnegative emotions in general as "toxic". Or, worse, avoiding people going through spells of unhappiness because their presence is "toxic".  This vigilance against "negativity" reminds me of the Victorians - except it's not sexuality the New Victorians are suppressing, it's their feelings. And just as the old Victorians shunned the "sexually degenerate", the New Victorians shun the unsmiling.