Because what you write can only prove that it is a loan from your company, you are a legal person, and this is your responsibility.

It's no use signing an agreement saying it has nothing to do with you, but the agreement must be signed to prove that he took the money.

Fortunately, his house is mortgaged. If he really doesn't return it, the bank will pledge the collateral first and then return it to the bank after it is processed. If it's not enough, find your company for the extra part.