I was going to post anonymous, but recovered my ancient log-in so that you'd at least have a "face" for this drive-by. I don't even know why I'm posting, other than my brother did something similar, but at least he had the minimum courage to tell his wife the reasons as he was leaving. I'd never been quite so disappointed in him when I heard he just walked away... So, what you wrote hit something in my heart of hearts, so, here goes random helpful internet guy...
I'm so sorry to hear how you were hurt. I don't know why people do hurtful things like that. There's no excuse for abandoning someone that cares for you and that you've cared for in the past.
I'm sorry the hurt is still with you. I hope you're getting help, and if not, PLEASE get help. Some may say it's appropriate for you to have problems while you "mourn" the loss of your loved one, but if you've been in so much pain that it STILL troubles your sleep, for over a year, that's not "normal mourning."
Your brain can do amazingly bad things to you, and like most brain disorders, it's really hard to realize that you may need help. The mind loves to lie to itself, to reassure itself that while things aren't "right," they're not *THAT* bad. But it might just be. You may need more than just *struggle* to get through this. I'm not talking meds (though they may help too, they did for my own issues), I'm talking a licensed therapist at the least, a shrink if you can get one.
This is a link to a project that looks to connect people with therapists who practice based on Evidence and published data. I'm specifically posting a link to non-religious therapists, not to cause trouble, but because even if you may be religious, and may indeed find a good religious therapist, it's also possible their beliefs may conflict with yours, and may cause more pain than balm. I think it makes sense to start with a therapist that doesn't even have religion as a component, then discuss introducing that as part of your therapy later, should you desire it.
As alone as you may feel, as worthless and petty as far, FAR too many people are, there are *good* people out there. People who can more than make up for the scumbags out there, who will trip over themselves to help you, if they just know you are in need.
If you're not sure you need help, if you think you're *probably* ok, or *mostly* ok, try to get help anyways... if you really are fine, than the worst that can happen is they agree with you, right?
This was a much bigger post than I intended, stranger/friend. And you may never see it or read it. I hope you do. I hope that you're not alone with your pain, and if you are, that maybe for a moment my words make you feel less so. And if you need it, I hope you decide my completely unsolicited advice is, instead of insulting, a kind-of tool, another way for you to help yourself.