I don’t know if there is a one-off solution to triggers.
What I can share is my experience.
I had some really serious triggers that were 100% connected to PTSD. For example: if I was in a confined space like a restaurant or bar, I had to sit with my back to the wall. I felt fear and apprehension if I saw a kid under 5 years play close to the sidewalk. Somehow magically if I knew they were six years or older – no anxiety. I felt physically sick if I saw pictures or images of brains on TV or museums or whatever. Same if I saw cauliflower (resembles brain…), even in stores.
I had serious trust issues that I associated with my experience in law-enforcement. I had an above-normal sensitivity on how people handled knives – be that in the kitchen, fishing or whatever. If the blade was in any way pointed in my direction I automatically adjusted to a defense-stance… When I drove past the apartment building, I was living in at my d-day I would feel queasy.
There were more triggers in my brain than there are at a live firing range…
About 15 years into my present marriage, and 13 years after leaving LEO, I got my marriage into such a stage that I realized I needed help. I went to an IC, certain that my LEO experiences were the main cause of my PTSD and my triggers.
After listening to my story and some tests, the IC pointed out that yes – my LEO experience had left some issues that needed dealing with, but the MAIN cause of PTSD was the infidelity.
Turns out that thing we expect might happen or are more "reasonable" are less likely to scar than unexpected issues. Maybe it’s like if you know your partner has a terminal disease and you have a year to prepare might hurt less than a sudden death. Like possibly being attacked is something that a cop can expect. Walking in on your partner cheating maybe not so much…
For me a combination of "treatments" worked. Not least simply the act of clearly associating the triggers with their causes and then distancing the trigger from a likely outcome.
Basically – we just talked each incident through and connected it to the event, the action I took, the reasons and why THAT incident did not mean that just because once I had an experience did not mean I would have a repeat experience every time.
I then went through a series of confrontational exercises. Like… he made me handle cauliflower and disassociate it from my visions of brain-matter. Somehow there was a click in my brain where I went "Bigger – this is just cauliflower…". Did this with several issues from the LEO days. I guess we handled that in 1-2 session. No longer assume a defensive positum if my wife’s carving a chicken…
Somehow understanding the triggers, what they were and what caused them, enabled me to remove them. Took time, took conscious decisions and exercises. Like if we went to a restaurant I consciously let my wife chose the table and accepted sitting with my back "undefended". After surviving a few dinners without being jumped, stabbed or shot, I sort-of started to believe that my insecurity and risk trigger requiring me to sit with the wall to my back wasn’t really sensible…
However… the infidelity took longer. Unlike so many here my marriage is not with the person that cheated on me, but I did take MY issues from the cheating along into this one. The key to the cure was the IC convincing me about the illogical act of expecting unexpected behavior and actions from my present wife, just because my former fiancé had shown that behavior.
So if my wife was working overtime, then maybe she was working overtime. Rather than jump to the conclusion she was two-timing me, then why not assume she was working overtime. Maybe call her at work (desk-phone) on some false premise and if she answered then believe the logical deduction, rather than imagine she somehow had her office line diverted to the bedside phone at the Shackup Motel. This isn’t letting my guard down, but rather avoiding assuming the worst out of every situation.
The IC also suggested (and I did…) a very frank conversation with my wife explaining the long-term effects of the infidelity. Just as I expected she correctly pointed out that she wasn’t the woman that cheated on me. I correctly pointed out that this was true, but I was still the same person as had been cheated on, and had taken those issues along with me. I would work on removing them, but would appreciate her understanding if I was feeling insecure.
I guess what you might be able to take from this is the following:
Your triggers are normal and probably to be expected after such a life-altering incident as infidelity.
They won’t go away unless and until you deal with them. Ignoring them won’t do any good at all.
My experience was that once they were put on the table, it was relatively easy to see how "stupid" and illogical they were, and find better ways to deal with them. Like the comments about the "side-piece"… maybe you should think in those situations how ill informed these people are and how their perceptions are far from reality and then simply put it aside until you are in an environment where you have more control.
Talk to your spouse. That ride home didn’ t have to be tense. Instead it could have been a moment where you make your discomfort known, how that is a consequence of the affair and you two discuss how you – as a couple – can handle these situations.