Hey there!! I had a cousin that was very attached to me as a child and teenager as we were only one year apart as well.. We would hang out all the time and were very physically and emotionally attached to one another.. However she got to the point kinda like you are describing where she always wanted to be together even as we got older and wanted to be with other friends and I wanted to go on dates and just have some good old alone time lol and she didn't really want anything to do with any of it she was fine with it just being us forever it seemed like!!! She was also hit by her dad.. Finally I needed some changes or despite my love I was going to be pushed away so I started out like kinda forcing her to do more group things with me trying to broaden her social horizans and what not I also got her to sign up for a dance class so I mean I think my advice just from experience would be try and seperated yourselves a little and give it some distance just do it in a nice way and over time.. You are his support and a huge part of his life you don't want to push it just alter it for now... He totally sounds like he does have seperation anxiety as you are never to old to have it, just more often in children is it seen.. Therapy I agree is also key to him being able to move on, and trust and be ablevto function in life etc...
Was your friend abused by his parents? Is there no help there?
As Paxiled has stated, your friend is in dire need of therapy and until and unless he gets it, YOU will remain his safety net. You have obviously been a VERY good friend to him through all the years with this, but the responsibility for his mental health is staggering and you must begin the process of seperating from him............AND BY THAT I DO NOT MEAN YOU SHOULD ABANDON HIM! You obviously care a great deal about your friend, and I think the time has come for you to help him get the help he needs. Yet another huge responsibility, but he apparently has no one else to turn to or trust. Again, as Paxiled stated, neither of you are young boys anymore and at 18 you are now on the verge of moving on with your life. I understand you love him like a brother, but you deserve your own life. I just don't want you to feel guilty that it is getting to be too much for you to handle. I doubt most people could or would have done what you did for all those years. I'm humbled by your compassion.
Can you enlist the help of YOUR parents to figure out how to get help for your friend? If not, is there another trusted adult in your life? An aunt or uncle, a teacher, a minister/priest/rabbi? While your friend is hardly a "child" any longer, he is still underage and perhaps the Child Welfare people could help you. If not, I bet they could tell you where to turn.
It's asking a lot, but helping him get the help he needs now may enable him to live a normal life. What an amazing gift that would be.
PLEASE let us know if there is anything we can do, even just listen. And hopefully someone on here may have some other ideas of the path you should take.
Take care of yourself.
Peace
Greenlydia
EDIT: sometimes *he would cry.
Thank you, Paxiled for answering.
Anyone can get that, but you've already answered your question. Your friend has been abused and you've been his rock. Until he finds a way to deal with what's happened to him he'll cling to you for the support he didn't get when he needed it at home. He's going to need therapy, and probably a fair amount of it, and that two year age difference is going to get larger as you move on in your life.