I read a book a while back, called "Highly Sensitive People" and it helped me a lot. I have gotten better over the years at not taking everything personally, but it was long hard road. You have to realize that people who are criticizing you, have their own issues, and sometimes criticizing others is a way that they don't have to look at their own faults.

Also, working in any environment where you have different personalities can be challenging. I work in a large office full of mostly women, and some of them act like they are still in high school-- grown women my age, 50 years old, who have bad tempers & can't get along with others. I have learned to tune them out by playing my music on my headset, & basically limiting who I will be 'friends' with in the office. Out of 30 people, I only consider 1 co-worker my friend, the other people are just co-workers that I get along with by not letting myself be pulled into their immature dramas. It takes a lot of discipline on my part every day, to not be bothered by their pettiness but it does get easier with more practice.
Wish you luck in your job! :-)