I did it (again)

I had a friend I have known for 10 years, I mentioned him before. I will call him M. M and I where so close as kids and basically grew up together. Over time that shine I saw in his eyes was gone and I felt so bad so I stared to give everything to try and make him happy. It was never enough even now. M was a really toxic person and im not going to say why but lets just say I tried to leave a few times but he had SOMETHING to say or do to worry me back to him. He has done other things but thats the big thing. But despite all this for years, no my whole life I gave him my self everything but still no shine. My friends opened my eyes and I realised I was so focused on him being happy i didn't take care of my self to the point where i dont know how to take care of myself. I finally sent him a message basically saying "man its been years and though i love the good times there is also some bad times thah haunt me ect" i said how i loved him and cared about him but now i just can't stay with him. Of course i wrote it in a different way but i don't want to post that on the internet. He gives me a shollow respone after my 5 paragraph text. It hurts due to me knowing him for so long. Its hard to explain. Its not just some friend im going to forget about when im old. I mean me and him where CLOSE but all the advice i get is "you will meet new friend's" it hurts so bad. All i wanted was to bring back that shine is his eyes almost dying in the process but it was never enough. So to M thank you but shit oh how it hurts.