Here's some tough love mixed with some of my own experiences.
My situation was a bit different than yours. My AXGF ended it in a very sadistic way which left no doubt as to what her true core was. And I said, Thank you very much, and haven't looked back since.
But there are others in my past, who aren't addicts, who left a bigger mark than my AXGF ever did, and one of those still hurts pretty bad. And I just simply sit with it. Sometimes I'll drive by her exit off the highway, and that triggers a lot of initimate memories. That actually happened to me last weekend. Went into town to eat at Morton's with one of my buddies from grad school, and I had to drive past her exit going home. And man, it was tough. But even though it still hurts, there is no question that it's over, and that it's for the best.
You invested a lot in this guy. And when something like that blows up in your face, it's going to hurt, and it's going to hurt for a while. There is no getting around it. Maybe you'll heal. Maybe you won't. But even if you don't heal, life still goes on, and you do the best you can. Which is kinda what you've been doing. Even if you're just going through the motions, you deserve a lot of credit for that.
With an addict, you owe it to yourself to do a post mortem at some point. You have to look at why you did what you did and see if you took a wrong turn somewhere. That's how all of us here at SR have grown. We f**k up, we look at how and why we f**ked up, we accept responsibility for those choices, and we grow. Growth isn't without pain. And although this hurts bad right now, trust me, this is nothing compared to what would have been on your radar if thing's hadn't blown up.
Just keep going forward. Fake it 'til you make it.