My question to everyone is: Without making threats or ultimatums, what can I do to get her to tell the truth? If it’s not possible, what can I do to wrap my mind around the fact that my wife is lying and that she will most likely lie to me for the rest of our lives?
Eric,
It is highly likely that you have married a woman of poor moral quality, and that she will continue to lie to you and engage in more of this same behavior. As Chatter says above, it's really up to YOU what you want to do about it. You've already basically eliminated not only divorce from your decision-making equation, but also even issuing any kind of a hard-line stance, so you're kind of tying the hands of those of us who might normally advocate some of the stronger approaches that I think are required in your situation.
The other thing that struck me is that several times in your long post you say "Needless to say, I didn't believe a word she was saying," or "I knew she was lying to me" and yet you continue to ask her for the truth.
The "I know all about ________, and it needs to stop. It's incredibly disrespectful to me and to our marriage" approach that Chatter is advocating is the best way to go, for sure.
What ARE your boundaries? What are your dealbreakers? You come across as a "I will stay married to her at all costs" type, and while I am STRONGLY pro-marriage (and successfully saved my marriage after my wife's affair 5 1/2 years ago), it's been my experience that those that approach these types of situations by immediately eliminating some of the tougher options . . . fail.
I'm not saying that divorce needs to be one of your options . . . yet. But you do need to have SOME non-negotiable "Boundaries of Personal Integrity" here. Not only have you been tolerating five years of serial infidelity and deceit, but she is also verbally abusive towards you.