Mr. Obvious wrote:
You are certainly more knowledgeable than I am about the law but I understood that the adverse spousal privilege survived divorce--for things that happened when they were married. I understood that she could be compelled to testify about things that happened before or after they were married.
Do I at least understand what you are saying, that the divorce changes the protected status of things that happened while they were married?
Although the law may be otherwise in some states, I believe that under federal law, the only spousal privilege that survives divorce is a relatively narrow one relating to "marital communications" -- confidential communications between spouses during the marriage. That's different from the privilege against compelled adverse spousal testimony, which applies to a much broader range of subjects about which testimony is being sought, but which may generally only be asserted to protect against compelled in-court testimony against the interests of a current spouse.
If there is, indeed, a federal criminal investigation targeted at Lance Armstrong, I doubt that spousal privileges will provide much of an impediment against obtaining some incriminating testimony from the former spouse. She may not be required to disclose "pillow talk" about Lance's thoughts on doping ("Y'know, honey, I've been thinking of giving up all of this blood doping; it's getting trickier to avoid detection, bribe officials, and intimidate witnesses"), but I'm confident that she can be required to testify about conversations that others say she was a witness to, and can probably also be required to testify about any doping practices that she observed ("Our refrigerator at home was always stocked with milk, eggs, and four pints of whole blood.")