For the best help you need a correct diagnosis - you really do need to start with seeing a dr. If you have to pay for it, it would still be worth the money.
You say your flashbacks and night-terrors often involve infidelity - a clue to what is going on. It lie in what else is in the flashbacks / night-terrors.
@franciemarnie is right - maybe there is trauma from childhood you can't yet remember - there might be other reasons for your symptoms, but in terms of PTSD, being cheated on cannot lead to that developing.
This is NOT to say your experience has not been traumatic. Someone can be traumatised and can have symptoms of trauma from just about anything - whether or not it is a Criterion A.
One example for me is as a child I experienced emotional, physical, sexual abuse. The physical abuse and sexual abuse mean I was diagnosed (based also on symptoms of course) BUT my EMOTIONAL abuse -
while it was very traumatising - cannot lead to a
diagnosis of
PTSD.
Another way of explaining it is this - if my childhood abuse had 'just' been emotional abuse I may still well have developed the same symptoms of dissociation, flashbacks, etc but even if I showed ALL the symptoms of PTSD, it would still not MAKE it PTSD.
So yes- being cheated on might very well have left you traumatised - but you cannot be diagnosed as having PTSD from it - this is NOT saying you aren't your thing or that you aren't suffering. But the only way you can heal is if you see a Dr for a full assessment, and diagnosis, so you can get the RIGHT treatment.
You say your insurance won't cover 'behavioural' health - I have no idea what that means but either way, y need a Dr to diagnose you - and it might end up being something that IS covered.
You won't know until you get diagnosed and a treatment recommendation made.
