Take it as an experience to learn from. It’s not easy to deal with people who we dislike or don’t get very well along with. This is the challenge that will make you stronger. Stand up for your place but be friendly.
Keep the idea that you are worthy and be yourself.

Meanwhile, to avoid your mind thinks a lot, first, don’t try to fight against these thoughts because they are gonna be there, but try to focus on something else without forcing your mind that it’s gonna play bad games with you by bringing these thoughts over and over again.

Also, and secondly, think about other moments you felt like this and then, you realised nothing bad happened and you even succeed.