Insurance company said they would file litigation against me.

I assume the insurance company you refer to is the one for the owner of the vehicle that was hit. Vehicle owners are responsible for who they permit to drive their vehicles. It is quite difficult to prove that a boyfriend or girlfriend didn't have permission to drive the vehicle in these situations. You will also have to prove how or why he was able to get his hands on the keys to your vehicle and that you were not negligent in failing to keep them inaccessible to your boyfriend. You need a lawyer in your community and hopefully you have insurance and have reported it to your own carrier. Your insurance carrier should provide you with defense counsel if you have insurance.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive legal consultation and review of all the facts and documents at issue. This answer does not constitute an attorney-client relationship.