Being a douche isn't a crime, assaulting anyone, even when that someone is a massive douche, is a serious crime, however.

Your belief is wrong, the aggravating factor isn't how severe the injury is, it's whether OP cause any bodily injury at all. Since there is injury, this is at the very least a class A misdemeanor or a third degree felony depending on which state OP in. Both of which carry jail time and fine in the thousand.

OP indeed will need an attorney. His best bet is that guy agree to a settlement. But even then, a prosecutor can still decide to prosecute OP anyway.