I work for an insurance company that's #78 in the Fortune 500 and in league with those like your insurance company,CIGNA. Indeed, see a lawyer, but about behavior of your doctor and his staff toward you - are you on a network plan, meaning, is this your primary care physician? Or, do you know if he's contracted with CIGNA to provide medical services to their members (your husband and you)? If so, contact your member services (the ph# is probably on your insurance card) and let them know what a jerk this guy is and how he's refusing to provide services to members (in violation of his contract with CIGNA).
Make sure you talk with your attorney, first, though. As was stated in the earlier post, there may be issues of a liability dispute if the person causing injury to your husband has insurance, and the 2 insurance companies (your's and their's) disagree. In that event, you may not want to reveal too much (or anything at all) at this point. You can always complain about this doctor anytime at a later date.
What this doctor is afraid is that, in the event this does go to court, he'll end up being caught in the middle. He may, for instance, end up having to testify but, mostly, he wants to avoid having to wait for your case to be settled before getting paid.
I hope your husband's quick recovery and, in the meantime, that he's able to find access to the treatment he needs. It's unfortunate that money still has greater power than God's gift of the power to reason.