Your sons are watching you. They will face betrayal or a huge setback in life someday, of their own.
You are modeling for them, what a man of strength and honor does, in the face of that.
True, you don't have a lot of property to worry about. But you COULD in theory, someday date OW who treats you a lot better. Otherwise you might be showing them that a woman can lie and cheat, in a serial manner, and you'll still be there. So there is a cost to staying... a cost to standing.
I know what you said about vows. I get it....I really truly do.
But there is a line somewhere, beyond which YOU cannot be crossed. Figure out where yours is, (and no, we are not going to tell you where that is, b/c it's so personal a decision that really you are the only one who can make it)
and we'll be here to support you. But do find a boundary somewhere internally. So you will know where it is and when it has been crossed (maybe already it's been crossed) and know what you'll do.
Also, 15% of marriages that divorce, end up reconciling after a divorce.
Maybe she needs to really see that the grass is greenest where it gets the most water.
And maybe you do too. Hang in there and keep on keeping on
