StillFrozen - welcome to SI, the best "club" no one wants to join. You will get a lot of great advice from folks who have been in the trenches of infidelity. Take what works and leave the rest behind.
Because I see some parallels, I want to share some of my story. It doesn't mean it will be your story too, but it's unusual to have a dday just before a wedding....
I also caught my WH cheating on the eve of our wedding. We had a fight, he was drunk, and he left, coming home in the wee hours of the am. Somehow, I later found a fishy receipt and turns out he went to a prostitute that night (who knew you could put THAT on a credit card?). I was also a single mom. I also went forward with the wedding. Flash forward nearly 25 years, and I learn he continued to cheat in some form or another during our entire M. It has been devastating. I feel that the majority of my adult life has been a complete lie.
So -my question for you is what is your WH doing to become a safe partner?
I see you are in couples counseling, but is he in IC?
He began with this woman only TWO months after you met, and continued for an entire year - including through your engagement?
That is a HUGE red flag, and given the timing strikes me as a bit of an 'outlier' way of behaving. IOW - he may have some very deep seated intimacy and honesty issues that have to be addressed, as that is the "good" time of a relationship (and the obvious next question is - so what happens in a decade when the bedroom is stale? Or the kids are in a particularly challenging phase, etc)
he was right there, trying to fix me. Making sure I was taken care of.
I had nearly 25 years of what I thought was a damn solid M. The kind of M that others were jealous of (well, still are, given they don't know what he was really up to). And my WH was EXACTLY as you describe - right there, trying to fix me, taking care of me, etc. Together, we built a great life, were VERY active in our community, and were wonderful partners - or so I thought.
The problem is that all of that "fixing" and "taking care of" was really hiding some pretty effed up ways of thinking, and some absolutely effed up ways of behaving - in secret, of course. My WH was doing what Brene Brown calls "hustling for his worth". A lot of his A behavior is motivated by being a KISA (knight in shining armor). He gets his own value from how he is mirrored by others - esp women.
He also has some significant attachment issues (read up on it, there's a great book called "attached" that I got from my library). While I gripe a lot about my WH's lack of work & progress, one thing he has learned from this rollercoaster is that he's been a liar his entire life, about anything and everything that causes him shame. He has NEVER been emotionally intimate with anyone - including me (tho I'm the 'closest' he's come with anyone). He learned early - and spent a lifetime perfecting - the ability to just not "feel" anything and to either bury it or lie about it when he did. He built a TON of resentment toward me, our family, etc.
If at all possible, I would ask him to see a CSAT (certified sex addiction therapist) for an IC. I would require a timeline of his A, and follow it up with a polygraph, bc someone who is willing to cheat and live a secret sexual life for an entire year during the "engagement" and "honeymoon" phases is VERY VERY VERY likely to cheat again.
In my sitch, aside from the ONS I caught him in, before we M he was ALSO seeing the XGF that became his LTA AP, and I believe others as well. He claims he wasn't sleeping with said XGF at the time - she says they were - who to believe? After dday I got more info about his past infidelities - turns out that EVERY relationship he's been in included cheating in some form - he was cheating, he was cheated on, or he was an AP. He still hasn't provided a full timeline, which is a precursor to the polygraph. I will probably D before I ever get the truth.
I sure wish I'd had even a remote clue about all of this when we'd only been M one year... and BEFORE I chose to have another child with him.
Listen to Dr Omar Minwalla's 3-part interviews on "Helping Couples Heal" podcast to learn about the "integrity abuse disorder" and the issues with having a secret sexual life.
This infidelity is entirely a "HIM" problem - it is NOT a "couple" problem. I suspect this is the last thing you want to hear, but I truly think it's really really unlikely that couples counseling will do the deep diving required to get him the tools he needs to also learn how to actually use in order to become a safe partner. Cheaters are really really good at "white knuckling" for a long time (like a dry drunk).
So. You asked about triggers.
The first thing is the dreaded four letter word: T-I-M-E. They do get better. I'd say I probably started seeing changes around months 12-18.
I also did EMDR starting around month 8. That helped.
There are other modalities in therapy that can help, but it mostly comes down to trying to retrain your thinking.
Are you in IC for yourself? Do you see learning of your WH's pre-M A as a trauma?
Have you read "how to help your spouse heal from your affair" by Linda MacDonald? which I'm told is available online for free. It's a pretty quick read, but is almost universally considered a "must read" on SI.
I would stay away from anything that outright or implies blame to the BS (which includes Janis Spring's After the Affair [tho some on SI got a lot from it], and anything by Esther Perel or Myra Kirshenbaum [tho again, there are a few SI folks who aren't as opposed as others to either of those authors - you can get opinions in SI's The Book Club thread).
Most ICs will see this as a trauma. Many/most BS' have symptoms akin to PTSD, some get a Dx of PTSD (I did). Whether you get the Dx or not, the point is that it seems the way to manage the triggers is to address the trauma of your WH's A. I have seen several so called infidelity "specialists", but turns out the best IC for me has been one who specializes in trauma - and I've just educated myself on a lot of the infidelity pieces. Marnie Breecker did a 2-part interview on Duane Osterlind's "the addicted mind" podcast that is all about relational betrayal trauma. It was the first time I felt validated... the first time I recognized that I was dealing with something beyond what I'd ever had to deal with before (and that - like most folks - includes a long line of curveballs). There is a thread about this podcast in the "general" forum that I will bump for you (but you may still have to "dig" for it, as the topics in general move down the list pretty quickly).
Anyhow, this is now super long.
Welcome. I wish you the best in learning how to recover from your WH's A.
And you will get plenty of others commenting too.
Godspeed.
ETA: I have bumped that thread for you. It's in general. If you can't find it on the general thread, you can still find it by googling: "surviving infidelity" "Therapists that get what a BS goes through".
[This message edited by gmc94 at 12:22 PM, September 23rd, 2020 (Wednesday)]