The real problem is not being allowed any boundaries, not being allowed any personal privacy, and then being persistently accused of things I'm not doing
I really understand this, too - despite my history of snooping!
I tried checking up on XH (I wasn't very good at it) because he was abnormally secretive - and, as people later told me, was cheating. It made him very angry and he gave me all the stuff about lack of trust destroying love. In fact he gave it as my unreasonable behaviour when we divorced. That's another story.
Simultaneously, he was reading my diary and using my private thoughts against me. He followed me and had me followed. I'm the opposite of secretive but his behaviours were more of a boundary breach, in my view, than my clumsy efforts to find out who I was living with.
When postcards arrived for him, I wouldn't read the message unless he asked me to. He found it impossible to believe anybody respected basic privacy that way, let alone the wife he had cast as a possessive lunatic.
As you can see, this was a hideously dysfunctional relationship. I hope you can also see why I say there's no black-and-white answer to your title question.
As you post a little more, a picture is emerging of someone with a compulsion to find secrets where there are none. If you can ever be satisfied that he's given up - or is restricting his activities to areas you find tolerable - then there may be a future for you yet. I'm sorry to say I'm not all that optimistic. It may be that your personal level of privacy is more than he can comfortably accept, or that his level of paranoia is more than you can.