CGs surround themselves with people who, verbally or non verbally agree to keep their secrets. CGs target those who will enable them to gamble. Usually, vulnerable people become entwined emotionally with the CG, who will continue to use those people or that person (you, in your dad’s case, JD)for as long as they allow themselves to be used.
We are only as sick as our secrets.
Ask yourself why you are continuing to be part of your dad’s secret life.
I hate to say this, but sometimes it suits the enabler to allow her/himself to be treated in this way.
You are NOT in control of your dad’s gambling addiction. You ARE in control of how you react to his demand for secrecy.
Perhaps you could tell him you intend reneging on the agreement to pay his loan and instead of involving your mother, you could let the creditors know who the real debtor is.
I have a little bit of “inside info” in this area. I have used your dad’s tricks. I can see right through him , even at a distance, because I too am a compulsive gambler.