How do I handle harsh or unfair feedback?

You can take feedback now, most of the time. It is the harsh delivery and the plainly unfair kind that still get under your skin. That is understandable. Harsh feedback stings because it feels like an attack, and unfair feedback stings because it feels like a lie. Both are hard to hold steadily. The move that helps is to separate the message from the delivery, and the true part from the false part. Harsh tone is about the other person, their stress, their poor skill at giving feedback, not a measure of your worth. And even unfair feedback sometimes carries a grain of something real buried in the exaggeration. Your job is to calmly pull out the useful grain and let the rest fall away. So when hard feedback lands, do not respond from the sting. Take it, sit with it for a day, and ask one question: is there anything true here I can use? Keep that, discard the tone and the unfairness, and move on. You are not obligated to accept all of it, only to mine it for what helps.