trying hard to figure things out

[TrentC]

It true I never trusted him in our marriage because I always felt that he was cheating or would cheat.

Did he give you any reason to believe this was likely (before now, of course) or was it a case of insecurity on your part?

You have control over one of those possibilities...

But he always told me I was wrong and that maybe when we'd been married 50 years then I would trust him.

It sounds like a self-fulfilling prophecy; you believed he would cheat, so you treated him as if he would cheat, and so ultimately he did cheat. Sounds like a lesson hard-learned.