RE: Ethics question, what should I do.....
Depends on the terms of the lease. To say the very least, this would constitute another hunter on YOUR LEASE. Based on that alone, you should be able to get at least some of your money back (particularly if you are not hunting there next year). If the guys is leasing the land and then his family hunts on the land, this is wrong, unless it ls spelled out in the lease. Typically,a lease gives you exclusive rights to the land.