Hi Bruce,
Here is something you could try to reduce the anxiety besides the self focus that is the healing, but I get that this is an external stressor that digs and erodes at you slowly so it impacts your work even when you are retraining yourself to get back into your center and peace.
I will try to be simple, it may or may not help you, see how it feels for your situation.
The trigger is simply something that hits our subconscious scanner for threats.
When the threats are not touching your life you have no such thing (you don’t watch for terminators every time you hear your ai assistant because you likely didn’t live through judgement day, no Schwarzenegger robot phobia).
When you lived through an existential threat, your lambic system is constantly on alert to some extent scanning the environment to prevent you from experiencing it again.
Usually you don’t worry our closest people may kill, rape, betray you or do any intentional abuse to you.
But you lived through infidelity, so one of the unthinkable things actually happened to you.
When a person experienced it once, from that point on Your system knows this person could kill you, your system knows this person might rape you, your system knows this person may betray you.
Because they proved you in the most painful and traumatic way, they are capable of.
You obviously love your husband, or you wouldn’t have ever given him an undeserved second chance.
Your lymbic system is now stuck between knowing that this man is "capable" of sexual and emotional abuse which is for you a kind of existential threat (while you likely don’t feel like he could kill you, rape you, etc the trigger is very specific to this person and what he did),
While
Your conscious mind has seen some progress and perhaps remorse or regret, that’s the part of you who believes he can change and be lovable, part of your life again.
Here is the dissonance that tears any abuse victim apart from the inside.
So what you do? Part of you want to trust and return to peace and safety with this person. The other part scans for any threat pattern reminiscent of when it happened.
In this case the work. (As in many cases)
A way to calm down the lizard brain who doesn’t think, only scans and respond, is to give it certainty.
Once it is certain it at least calms the anxiety.
The lymbic system was conditioned by the trauma of infidelity.
You can condition it to stop torturing you.
Is not logic, is not fair or reflective of reality (your husband might really be changing), is just conditioning against the trauma conditioning.
You know this person is capable of infidelity.
Assume that every time your back is turned he is indulging in infidelity.
No matter where or when or with who, every time he walks out the door, he is doing exactly what he did.
Your trigger will calm down immediately.
Again, and this is very very important:
This is not the truth or meaning he is still a cheater. He could be a completely changed man. He could be a safe partner. He could be more repulsed from infidelity that you are.
He could be a good person, sincerely reformed.
This is relevant for your aware, emotional part, but is irrelevant for your lymbic system.
Conditioning the,lizard brain to accept that the threat exists and is exactly as bad as it felt, and is forever present until this man is at your side, makes it calm down for a canning for the threat.
Because it is recognized and present, it is accepted, there is no need for it to waste energy in keeping alertness. So it will calm down.
It sounds unfair but it’s not, there is no judgment only intentionally reconditioning what was unintentionally conditioned by trauma.
You can observe your wayward husband behavior and keep healing both of you towards reconciliation.
When some day comes where you truly healed enough to feel true safety again, the lymbic system will naturally recondition itself from "he is a cheater" to "he is no threat" again.
But I don’t think you can skip this step. Not if you want to remove triggers, at least. Conditioning to accept the person who abused you is an abuser and that happened intentionally, willingly, strategically, simply sets the lizard brain to see the person for who they truly showed they are.
They aren’t safe, they’re at it, no need to keep checking, you know what they do, they are predictable. And predictability is not a threat.
No threats, no triggering anxiety.
The unknown is what is scarier than the known one.
If you can keep the conditioning of the nerve system separate from the serene judgement of your husband reforming process it should shut down, or at least calm, so it will not drain energy from your healing and reconciliation.
I am not saying it’s easy, but ain’t hard either.