The perceptions of what others may think about you and their inability to see your value doesn't define your worth. You are essentially worthy, for your Creator who made you calls you His masterpiece and He knows you best.
People who choose to stay hurt, hurt others. Their negative words is like a knife cut to your chest, and the enemy will take those words to magnify the impact and bring forth bitterness, unforgiveness, hatred, etc into your life with that aim to bound you in his chains. The enemy wants to steal, kill and destroy you - he knows his time is running short.
But knowing the truth of who you are sets you free. You are able to live in that abundant life Jesus has for you. The wound will longer stay a bleeding and stinging wound; just a scar that doesn't hurt and reminds you of how strong you are and how far you have overcome. And you are still beautiful even with that scar.
So c'mon. You are better than what others think and even what you think you are. Don't change yourself because of others' negativity. If there is only one reason why you should change yourself, it should be because you want to be changed more in the likeness of Jesus. Live meaningfully with eternity in mind.