i dont know what you are trying to do here but it seems fishy on both sides but it is clear based on your post that the borrower should send his payment to the sending address of the transaction above which appear to be "1DFnLMuX3JzmPsGHx7F8KYFrG1dgXZrkcP"
and the transaction ID you posted here isnt connected to any of the addresses in the transaction you posted
I have checked tx id of loan and repayment and found there are 3 different bitcoin address used by lender
1C5EUDJYFZxm9D7UGD4fTRm1mjNArLvuS
1AwUL8sMtoFEUTCJMPefpEPZ8xeu1M7FjQ
1DFnLMuX3JzmPsGHx7F8KYFrG1dgXZrkcP
address that used to send loan and get repayment belongs to address from this list of address of lender so for me it looks ok with repayment, but I can't say anything about signed message from OP to lender