Negativity affects me greatly. I'm a very positive person, I always think the best of others and of most situations, so negative reactions to me or my work used to affect me a lot. I used to get paralyzed by anxiety and, in a later stage, I started to hurt myself by banging my hand violently on walls.
One day I was having a crisis and I banged my hand so hard that it formed a huge lump. Suddenly I couldn't really hide it and that was my wake up call.
I was already in my 30's when I found productive ways to deal with anxiety. Dale Carnegie's book
How to Stop Worrying and Start Living was a huge help (skip the "pray" sections, it's still very useful). The "worst case scenario" theory is exactly what Chemda was talking about.
Also I just found peace in the notion that you will never change others and you cannot control what others think or do. By controlling your own behaviour you take control of everything: I don't gossip, I speak my mind and I work honestly. I don't break the law and I live for my personal goals and my family's happiness. All the rest is white noise and stuff I cannot control. And that's fine.
I now have a new job and sometimes anxiety gets to me, I still find it hard to deal with my own mistakes and people calling me out on them. Still, I feel like I'm so much better than before, I stay bummed for a couple of days and then it's all good, it's not my bliss, it's just my job.
Try to read the book, Danny. It's all online, there are many websites that break down the principles. It's really helpful, I swear.