How can i stop being anxious and jealous?

Me and my Friends have become a little distant after i got back off holiday because ewe had all left school so we wasn't together all the time. We are all close friends, but they are best friends. However, i have really bad anxiety and over yze everything e.g. my friend gave me my dresses back but i though she only gave them to me so she has no more things of mine, if they do things without me i immediately think they are trying to get rid of me. It is putting a huge strain on our friendship. How can i stop being anxious and jealous?