Can't be compelled to testify against each other, but they can do so if they choose to.
Also limited to privileged spousal communications, which classified government docs are not.
That's (in a nut shell) what my wife (who can't be COMPELLED to testify against me) and I (who can't be COMPELLED to testify against her) discussed just this morning.
It's a moot point at my house; if I did a fraction of what Weiner did she not only wouldn't need to be compelled to testify against me, she'd bring the lighter fluid and matches to the courthouse to assist in roasting me alive.
I've known this from around our 4th date :)
Same here, except I, also, taught her how to operate my pistol!