Im having a hard time letting go a friend, need help getting pass this?

My best friend davon and i are really becoming further and further apart by the day. We was friends since 4 yrs old we were so close it was crazy if you seen one of us you seen the other. We start separating when he got his first real girlfriend they was having sex and so on so i guess he couldn't help being whip. He started to stop talking to me for an while at one moment we didn't talk for three months and i would call him everyday but no return. Then his phone kept getting cut off and i thought he was doing it on purpose to not talk to me. He had an girlfriend that i didnt meet ever and they was going out for 18 months i felt as if he was scared to bring her around me like i was going to take her away from him. I was kind of mad cuz i wanted to meet his lover but they broke up before i got the chance. Now he started to go out with this girl in may of last year and he then really stop talking to me she had him on a leach anytime we had plans to do something he call me back saying i cant me and my girl doing something. This really piss me off i tried to tell him but he brush it off and brought up another conversation. I just said **** it then he stop watching anime like me and him once always got together to watch anime from death note to toradora and the big 3 yes only english subs. He started to once in awhile watch anime it hurt a lil cuz that was our greatest thing we did together. Now he smoke weed from time to time, drink liquor all the time and hang around the wrong group now. It is really hurting me that we are splitting apart and it seems that he dont want to be my friend no more i did everything to try and work this out telling him how i feel, try to setup double dates with me and my girlfriend with his, come over his house but he say hes got stuff to do. It just hurt that my very first friend and i are becoming so far apart. We dated twins before, lost our virginity to the same girl at the same time, he got me into anime, he was the first person i fought, and he protected me when people trying to fight me i just dont know what to do please help. I have sort of an new best friend but im in love with her but its not the same fun.