I was in the EXACT SAME SITUATION with the previous position in my company. For 9 years. Every day felt like I had to be someone else. Or many different people! It was a customer service position in the medical field so I literally had to teeter the line of doing my job medically- which in itself people get upset over when they dont hear what they wanna hear- and making sure patient's were able to do the "customer is always right" crap even when they were wrong and stepped all over my feelings. That in itself cultivated a culture of identity crisis for me. But I also was a floor supervisor so now I had to manage my "coworker friends." I was never a hardass to them so I always wondered if they truly liked me and thought of me as a friend, or if they were just being cordial to their boss. So I wasnt sure how to act around them. It was the planet's lining up to make this toxic personality mess for me,personally. I found it affecting my mental health- literally having to prep myself to be someone else for 8 hours a day, 5 days a week- it was adding up and I could feel my tension rising. So I found another position in the company- non management but same pay and working from home.
Long story short- I TOTALLY get what you're saying. I've been there, you're not alone. It really sucks.