I went through a similar thing with my ex. He was a huge part of my gaming life so when I cut him out I could barely even look at my computer. Took me a month just to turn my PS3 back on because not seeing him in my FL upset me- still does a little and I still find myself waiting for my skype to ping even though I've completely unistalled it.

It'll pass. I know that doesn't help right now but it is the truth. This person has been a big part of your life for a long time, it takes some adjusting.

I would also like to say that I don't think this is entirely your fault. It sounds like you've done you're fair share of supporting him too and his own actions kind of show him to be someone you probably couldn't have relied on anyway.