How to approach long time (ex)friend?

Going to explain this the best as I can. So, I "have" had this bestfriend since middle school. We grew up together throughout the remaining school years, graduated and remained friends for many years since. It's been well over 10 years since we met. He basically became part of my family, he considered my siblings his, my grandmothers his and they did the same, he was like my brother. Every time he needed a place to stay, we let him stay with us, whenever he needed people to talk to, we were there. I considered him my real brother since we became best of friends, but..

Probably around November of last year, he just went away. Never really spoke to me, asked to hang out or do anything anymore. He had a kid during the summer of last year, I was the first person he told when he first found out his girlfriend was pregnant. Ever since he got with that girl and had the kid, he changed. He even told me before he was born that I was the kids aunt before he changed. Which really made me feel good. Then in November, him and two other friends (they basically did the same thing as him) all came to my house, didn't even know who all was there. They basically weren't close to one another, but stayed somewhat connected through me (although one of them hated the other one until then). After that, they all three began to buddy up and I became an afterthought. Since then, none of them has asked to do anything, and none of them have even really talked to me. But, back to the "brotherly friend". I approached him shortly after about what happened about why don't we do things or talk anymore. He claimed it was because of his kid, but he has been hanging out with other people including the two that were my friends that met up at my place last November. I never got invited to my "nephew's" birthday party or anything, it's like I no longer exist to him or the other two.

About a month ago, I saw him where I work, he came in shopping, he walked right past me and never said a word to me, like he didn't know who I was.. a "brotherly friend" of ten years..

Recently, it's been killing me and I want to get to the bottom of it which is why I'm asking for some advice on how to approach him (maybe one last time).

Sorry if this is difficult to make out, I'm not really good at explaining things. But, all help is appreciated.

 

I should have made myself more clear.. :s I don't really know if I want to be friends with him or the others again, I really just want to know why it happened like it did. Did I do something? (can't think of anything but it maybe why). We remained bestfriends even after high school, we graduated in 2010 and the fallout happened just last year. I understand people have priorities later in life, such as kids, relationships, jobs, etc.. but that doesn't mean you have to cut someone out of your life, especially when they were viewed as part of your family for ten years. I'm definitely going to say something to him, and maybe the other two, but I'm at a loss for words (I don't socialize often). :s Thank you for the reply!

 

I ended up messaging him last night before I went to bed. He replied, saying it was all his fault and that he was sorry for neglecting the family and myself.