<human>: Can you give me the gist of the text in a nutshell?

A little back story. I'm from NY and I moved to the middle of nowhere, Canada to be with her. We've been together for 7+ years. The past few years have been rough. She was really sick for a year and a half, I've been miserable and somewhat depressed because I miss home, but we've always worked through it. Unfortunately my version of working through it recently has been being a miserable prick towards her and in general. 

I have, in the past, gotten caught talking to other women online. None of them even remotely close to where we live. I used to have an opiate addiction in the past. I mention this because, when I got depressed, that was my fall back. Now when I get depressed, it's talking to other women on the internet. I get a rush that's not so different than when I would pop an Oxy. 

So this brings me to today. I just graduated college. I have a good job. I'm surrounded by mostly wonderful people. My mother just came up and visited me and came to my grad. But still.. I have had this nagging depression for a couple of months. So while I was asleep this morning. My fiancee went through my phone and saw some messages to another woman on Facebook. Needless to say, she has basically ended the engagement and walked out. 

I love this woman with all of my heart. I know what I did was incredibly hurtful and I deserve anything and everything she decides to throw my way. I need to fix this. I'm completely and utterly lost without her. Besides not talking to other women on the internet (I've already deactivated and sent in a request for a permanent deletion of my Facebook page), I know I need to stop being such a miserable asshole. 

I need professional help. I need to figure out a lot of things about myself. I need to figure out why I don't treat her the way she deserves to be treated. I need to figure out why I resort to talking to other women on the internet when I get depressed. I need to fix my shit so I can fix our shit. 

I know this is more of a vent than anything else, but I could really use some advice..
<bot>: Fiancee caught me talking to another woman on Facebook, ended the engagement, I love her and want to fix it.