The person of the critic.

The worst part about having a critic isn't what they think. It's not their critique, not their disparaging influence, their pretentious condemnation or even the panic they induce; for as our own worst critics those things already lie within the realm of ourselves.
Rather the bitterness is what is worst.
We're already in a heavy battle; we're grieving beyond their consideration, fighting for truth beyond their recognition, and making amends beyond their limited perception of the situation. Still, they have the audacity to judge the glimpse of something they callously misunderstand. We feel they've created a less than human identity of us that only includes our mistakes and the pain we've inflicted and certainly never lends us graceful opportunity for growth.
So in anger, injustice and defense we embitter ourselves towards them. Not just the injustice, or the pain caused - but towards them, the person, as well.

Bitterness is the worst part.

Our response to injustice becomes just that, injustice. We create a less than human identity of them that only includes their mistakes and the pain they've inflicted and certainly never lends them graceful opportunity for growth.
Does the last sentence sound familiar?

That is why bitterness is the worst.
It inexcusably demeans their personhood.
Then we become the very thing we find disdainful in them.

Value their humanity, not their callous critique.
Disregard their critique, not their precious humanity.