Help me please! i dont know what to do!?

k, so heres the thing, theres this boy, and hes been my best friend for while now, then we became girlfriend/boyfried.and a few months ago, i introduced him this friend of mine. we all go to the same school and meet in the park evey week. but heres the thing: lately, hes been hugging her hugging her a lot and leaning in close and stuff like that. they have also begin talkin a lot with each other and pretty much leaving me out of their conversations. so i talked to my bf askin if he like my friend. his answer every time is: " shes like a sister to me" I dont want to tell them to stop being real close to each other but then i would be a bad friend,and i want the 2 of them to be friends. there is this other dude, who is like a brother to me, so i talk to him a lot. but i dont realy see him much, only a lunch and at PE. and i NEVER EVER hug him, because i know that my bf would get jealous. and i dont want to hurt him. i have tons of friends who r guys but i keep my distance from all of them. i talked to my other friends about my bf and my friend, and they said tat i should ditch the guy who is like a brother to me. they think that my bf is like flirting with my friend a lot to make me jealous since i talk to that other dude a lot, but i dont get it, i still pay full attention to my bf and i never hug that other dude. what do you think is going on? im not sure of anything and i just want my friend back cause shes been my best friend since forever and i cant live without her as my friend, my bf is like always getting super close to all of my friends. k. thanks