He did commit the crime, so , making a claim on insurance (your insurance) seems to be the reason you'd want to avoid fraud.
Time to step up and do the right thing.
The consequences would be that he will be charged with theft, and his defense was that he had your permission. Tell your boyfriend what your insurance company wants you to do, and ask for repayment. If he refuses, and if you want your money back, then go ahead and file the police report.
DISCLAIMER: David J. McCormick is licensed to practice law in the State of Wisconsin and this answer is being provided for informational purposes only because the laws of your jurisdiction may differ. This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. Under no circumstances does this answer constitute the establishment of an attorney-client relationship.
Did your boyfriend use your car without your permission on prior occasions? You may want to discuss this issue with an attorney prior to filing a police report.