her best friend it's a guy

Hello , so my name it's Andrew ...... im 21 year old and i have a pretty new relationship with a girl ,the problem is her best friend it's a guy.I am jelouse .....i told her that , she explained me that they are best friends like from 8-9 years ago and he has been always there for her , without getting angry and upset , we talk freely about everything, should i worry about it? what should i do to keep my mind off that .... because he helps her alot with studying , homeworks or whatever she needs , i meet him he is a really nice guy , but she is with me now..... and still paying attention to him ... like touching him on the shoulder, hugging him when she sees him i am going out of my mind at the moment.it's really awkward for me ..... i was hopeing if she needed help for something i can help her she would ask me but she asked him .And from time to time they meet for a walk and talk.I feel awkward its' my first time my girl has a best friend a guy and she is talking with him a lot , paying attention to him , should i worry? i really need some help:)