The unfortunate reality is that the friend is likely a tenant at this point, and the OP thus has similar duties to a landlord.

And yes, it is a scam, and it is unfair. But as landlords, we frequently have to resort to cash-for-keys to get unwanted tenants out. Writing a check to get a tenant out is in most cases both cheaper and safer than waiting out an eviction process while a now aggrieved tenant does everything in their power to punish your home for the next few months.