I understand your points taxing matters but when you view it from a
common sense approach, a stranger gifting money for no reason is very difficult to believe. Regardless what the op claims, if this were to end up in front of a jury, the situation could be hard to overcome. If it came to believability of the parties it's more likely a jury would not believe it was a loan.
As to the discussion of repayment; we have the op's obvious self serving statements and nothing else.

