Undecided Question

my boyfriend's bestfriend is a girl and thought he has only known her for less time than we have been dating, he seems very attached to her. i wont have asked or care if they acted like just friends.they write things like i miss you, xoxo, xx etc to each other when talking and texting.he buys her phone cridet few times actually and have caught up on the train etc. my bf is known for buying girls cridet or giving money infact and catch up even with them and even stayed over at ones of the girl's place and says he is just friends with them. we barely talk, go out or even have sex. he is always sleeping in and if not doing that he would be playing games or just be lazy around the house. another thing is as soon as i am out of the house his texting with his so call friend starts and he hides his phone. when i tell him to delete the number and stop texting her as we have been in a bad fight before due to his so call friend he says i am just jealouse, controlling and braindead. when we had the fight i mention above he said her friendship was worth more than me and we have been together for nearly 2 years. i need advice to what i should do and if i am really paranoid or jealous to tell my boyfriend i am not comfortable with his relationship with his so call friend that he has known for a short period of time! oh and he never mention me to any of the girls till i got sick of their texting etc and i texted his friend (the girl) to tell her to stop whatever's going on becuase my boyfriend was in a relationship. when he found out the texts, he nearly skinned me alive as he was very angry and violence.