I think everyone deals and heals differently and a number of factors play into the recovery time such as personality, support network, outlets, and the nature of the relationship with the stbx to name a few. I am really only 14 months post separation but I've moved on in many ways and don't think of the betrayal hardly at all. It's more of a mental exercise in self-worth and I find humor in the whole situation.
4 years before the affair that ended my marriage, my ex was caught in an EA with a coworker that looking back was probably more. Discovered in March of 2007, took a few weeks for him to agree to marriage counseling and go no contact. Felt like crap for more than a couple months, and honestly my feelings and relationship were never the same in hindsight. By June, we decided to try to get pregnant (yeah I know, dumb dumb dumb) and seemed to be closer than ever, recommitted to the marriage and not taking each other for granted, quasi-communicating (or so I thought), and spending time together. We did get really close and even a year or so after the birth of our second child we seemed closer than ever, circa early 2009. Time goes on, and day to day routines interfere. I was able to trust him for the most part, he was pretty open and gave me passwords and things, but worked a LOT which fed some insecurities. Felt like we were growing back apart again around summer 2010 and tried to communicate about it where he went on and on about how he wasn't happy with life and his job and money and so on.
The second affair wasn't a huge Dday type ordeal where your world comes suddenly crashing down. It was a gradual event. He reconnected with his HS sweetheart on facebook around October 2010, and I had suspicions around Thanksgiving that they were becoming involved in an EA of sorts rather than just a friendship or "catching up". He bought a plane ticket to visit her in January and our problems started because I felt he was choosing her over me, he manipulated me into thinking I was crazy and had trust issues and then tried to take all the blame because of his prior affair. It was a total mindfvck. He then promised to work on our marriage around Christmas, but then all this was still going on with her, he was just hiding it. The more I snooped the more angry and "depressed" he got. I never found solid proof, but enough red flags to light a fire. He couldn't handle the pressure and moved out in March 2011 to "get some space and think and figure out how to work on us". Within weeks, things became heated and he stopped talking to me. I was in limbo for what felt like forever, which is the absolute worst. He still has never said, to this day, that he wants a divorce.
So timeline wise, I'd say that my depression and all hit at the end of November 2010 when I got that horrible gutwrenching feeling in my stomach that he was up to no good, and for months I cried daily, got angry at him, felt worthless, had a hard time eating, but I slept hard. I never had trouble sleeping, except for a one week period when things were at their worst. I got false hope for a period of like a month where everything was looking up, but then crashed hard soon after. I vented to friends, came here a LOT. I lost weight, tried depression pills (weren't for me) and then just hit survival mode at one point. By April 2011, I was on the way back up. Things would knock me down, but for the most part I was getting stronger day by day. I became very familiar with a group of people here on TAM that were on a similar timeline, and we formed a facebook group where we got even more familiar with each other and forged friendships. I started going on dates with the opposite sex by June, and I went and spent a lot of time with friends and family and rediscovered ME. That helped me a heal a lot. I met my boyfriend in July, who happened to be one of the members from here on TAM (hehe). It helped to have someone who I had forged a friendship with and had leaned on. The support network I had couldn't be beat.
As time went on, I was able to realize that it wasn't the end of the world. Yes, it sucked, and I felt horrible that my kids would have a broken family. I mourned the loss of those dreams and aspirations and then realized that while I felt like I wasted 15 years of my life and 10 years of marriage, I had two beautiful children and a lot of life to live at 32 years old. Once I embraced that it was easier. Ex ended up moving his skank here and they moved in together in August, and he still denies cheating. My only bitterness stems from that , mostly. But as far as personal healing, I'm not done, but I'm most of the way there. It will always hurt, but I know that it happened for a reason. And honestly, I'm glad to have gone through the experience because I'm wiser and stronger because of it. I wouldn't wish it on anyone, but it is one heck of a lesson in growing up. I feel much more centered and whole as a person and I'm able to look back and see mistakes on both of our parts. Mistakes I wish to not repeat. I can see warning signs in my ex, and now know what I want.
Short version...I feel pretty damn awesome at 18 months post "discovery of suspicious behavior". And I'm glad to have gotten rid of that piece of trash because I certainly upgraded.