I don't think I've ever known anyone who was addicted to gambling who didn't think their luck would change and eventually they'd win it all back. But it almost never happens, and the results can be devastating - as you have discovered.
Let me urge you first of all to face your situation honestly. It won't be easy to confess what you've done to your wife, but you will need her help in the months ahead as you try to repair the damage, and you'll only make matters worse if you continue to deceive her. Let her know you deeply regret what you've done, and you need her help and encouragement.
Then face honestly before God what you've done. Greed has been behind your gambling - but greed is like a cancer in our souls, and it can destroy us. The Bible warns, "A greedy man brings trouble to his family" (Proverbs 15:27). It also says that greed is a form of idolatry, because a greedy person ends up worshipping money instead of God (see Ephesians 5:5).
Most of all, repent of your sins and commit your life to Jesus Christ. He will forgive your past and give you hope for the future. He also will lead you to people who can help you with your addiction to gambling, or will counsel you about your financial problems. The months ahead won't necessarily be easy but it's far better to face them with Christ than without Him.