"YES, I realize that I should not have started living with him while he still owes me money. "
You want to help him but you can't. This is his problem, you cannot stop it, fix it or help him. He's the one who has to reach out for help -- qualified help. this makes you question how much he cares about you? Nothing is more important to an addict than his drug - in this case, gambling. An addict will do/say anything they have to in order to protect the object of addiction.
My suggestion? Either move out or have him move out, loving with an active gambler will only drag you in and drag you down. A gambler has the ability to drain you financially too, you may feel you're safe but you would be surprised what they will do. As long as you're this accessible to him you're in financial danger. Also, staying supports him, keeps him from having to face financial responsible.
He recognizes what gambling has cost him in respect of what he wants, but that isn't enough to make him seek help. There is no reason to believe that he will ever stop, many never do. As long as he is not in recovery, there is no future with him. I'm sorry, I know it's not what you want to hear, but wanting things to be different won't help make it so. All you can do is face reality and act according to it.