If you've been sued you should immediately contact a lawyer. Most lawyers, and I, would suggest you do NOT discuss the case with ANYONE, especially not the insurance company ever again!
It sounds like you might have some good defenses to any lawsuit, but you should NOT try to defend yourself against a well represented insurance company without an attorney.
Insurance fraud is actionable if certain elements of proof are established by the evidence. Using the written documentation you have is a good place to begin. Contact a local lawyer - many may give you a free consultation for an hour - to discuss your specifics. Far too many variables exist in the short post you wrote. You have to defend yourself so get a lawyer. There may be good defenses based on what you do describe.
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