Your attorney should be able to limit the damage if not prevent the e-mails from being used as evidence. If you don't have an attorney: get one.
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Get an experienced divorce lawyer in your to review the case in person. Not so easy over the Internet, bear in mind can she access more than the emails? How about where you go on the Internet such as AVVO?
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The criminal question would be difficult to answer. I'd say that it is highly unlikely that she could face any actual criminal charges. What she's done may or may not violate certain state and federal statutes, but the more pressing issue is, "what did she find?"
Family courts really don't care much about the parties. They worry about children, and distribution of assets and debts. Family Law courts are given wide discretion to see evidence that would probably not be admissible in other cases. So, if she found evidence of something that would call into question your ability to provide a healthy environment for raising children, (i.e. criminal activity), then I'd wager a court will look at it, and consider it. If it's more like evidence of an affair, used as part of an alimony claim, then the Court would be more likely not to admit the evidence for that purpose.
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