They do it once, statistically they do it again. Kick her out, start again, your pain will be justified in a few weeks. No use living in misery for something not your fault, you could drop dead next week. Relationships are built on trust, you no longer have that, and although some women can forgive, men usually can't, as it is a pride thing.
As Joe says, 7 years here, first one.
I would imagine that the stats on adultery are the same for most countries.
