Oh my word. £49,000? Plus interest, plus his wages? Forty-fucking-nine fucking thousand fucking pounds!?! What a selfish, stupid wanker of a man.
When you're dealing with someone with an addiction - and acts of this colossal stupidity sure sound like an addiction to me - you have to learn to ignore what they say about what they've done or what they intend to do and, instead, pay attention to their actions. The reason being is that they lie. They lie to you, they lie to their friends, they lie to everyone. But most of all, they lie to themselves.
This is the third time he's pissed away huge sums of money, lied to your face and broken your trust. The only "improvement" each time is the amount of effort he puts in to hide what he's doing from you.
More than anything, the way he cannot even admit he's got a problem reveals volumes. From his point of view, he doesn't have a gambling problem. What he has is a "keeping Snowflower sweet" problem combined with a "shit, I got found out before I managed to win back all my losses" problem.
Is his mother going to bankroll all his gambling debts from now until the end of time? No? Then her opinion is worthless.
You ask how he can see the reality of his destruction. So far, he's not had to. So he's lost a lot of money. To a gambler, money is merely a means to an end. If you've got it, great, you can gamble with it. If you haven't, you can't. Everything else comes a very distant second place.
Plus he's lost a lot of respect from you but, frankly, you're not important enough to him for that to matter that much either. It's nothing personal against you, it's just how addicts are. And you're still there, aren't you? So you're pissed off with him. He knows that he can talk you round because he's done that twice already.
As a wide, sweeping generalisation, addicts typically stop when they have lost so much that they simply can no longer face risking losing anything more. All he's lost so far is money and it is clear that that's not enough to make him realise what a twunt he's being.
More to the point, do you really want to remain with this car-crash of a man? He's repeatedly demonstrated that he is utterly untrustworthy and an accomplished liar to boot. You'd be a fool to even consider trusting him again. If someone's put that much effort into showing you who they truly are, it's time to pay attention.
He's a millstone around your neck. He will drag you down with him. Sometimes you have to just let go.