Struggling, don't know what I am

So one of my coworkers who became a close friend (or I thought he was) means too much to me. We got close cause of our shared interests and we would text a lot. Play video games, hangout at work, go out to eat, hangout etc..A new kid started at work and we started hanging with him too. I was sorta getting jealous so when they left me out I got mad and upset with my friend. I kinda got replaced for a bit. When I got upset about it my friend seemed to be annoyed with me. Even though he seemed to care about me more than my other friends, it's hard to describe it's just different.Anyways I'd get mad and ask why I didn't get invited and stuff and he'd always have some excuse. I'm pretty sure it was cause the other new guy didn't want to hangout all three of us. I was fine hanging with each of them separately and we did just that sometimes but new guy only wanted to hang with my friend by himself. It hurt to seek them together and to see my seemingly best friend replace me. Maybe I thought more of him than he did of me. It just seemed different and I know I was one of his only friends he actually hung out with on a regular basis.During the prime of them leaving me out my friend went about a week of mostly ignoring me and it hurt pretty bad. He later said it was cause of our last argument he was upset. The arguments always start as something so trivial and mostly cause I was being left out. I don't know it's a hard friendship to describe. I'd get mad and ask why I didn't get invited and stuff and he'd always have some excuse. I'm pretty sure it was cause the other new guy didn't want to hangout all three. I was fine hanging with each of them separately but new guy only wanted to hang with my friend by himself.We were all friends for a few months and then me being replaced lasted a couple months. It was the most depressed I'd ever been. Flash forward a little and the new guy at work moved a couple hours away and at the same time my friend got a GF.Now he is always busy with her and never has time to hangout or anything. We still text/Snapchat probably once a day and talk at work but he doesn't have time for anything. He says stuff like "oh we should do this" or "oh we should do that" but when it comes down to it we rarely do cause he's always so busy.Pretty much I don't have too many close friends that I felt that close to and hung out with regularly, so he meant a lot to me. I felt like I had known him way longer than I did. We bonded on a different level than my other friends and I. We have literally all the same interest and hobbies and we just get each other, or at least I thought we did. I know work friends don't mean much but we have always been more than work friends it seems. He turned into a friend that I happened to work with, not a friend from work.It makes me so jealous and upset when he's with his GF or he is spending time with other people at work. I used to be his go to friend now I'm kinda pushed aside. It still seems like he cares about me. I'm not gay but it's like we have a special bond. We get each other( or I thought we did) Not just some friend that I only hangout with to do a specific hobby. It's hard to explain.Whenever he doesn't reply(started happening when he got a GF) I get so upset. I feel incomplete without him. Like when we are together it's awesome but when we're not I wish we were hanging out most of the time. I don't know why I'm so attached to them but it's hard to explain.We used to kinda have a bromance going on but now he's kinda not as close with me. I feel depressed without him. We used to text a lot. Always hang together at work. If we weren't at work we'd usually be hanging together. I thought maybe we were so close is because he doesn't have all that many close friends either. We have the same small little friend group as well. However all of us don't hang all that much it's hard to get everyone together.It just hurts not being asked to come over, to play PlayStation, to go grab fast food, to go do something. He felt different than all my other friends and I'm alone without him.I know him and his GF are still in the honeymoon stage cause they just started dating but he doesn't make any time for anybody but her. I don't know how to cope without. I don't know why I'm so attached but part of happiness depends on them texting me and talking to me etc.TL;DR Friend always busy with GF. Had a bond with him that was special. Feel depressed without their companionship. No one can fill their place.