National Problem Gambling Hotline - 1800 858 858
Here is a number you can call for advice. I would strongly suggest you seek out counselling services in your area and get DH to go, he needs professional help and the sooner the better. I would tell him you will stay but you need to see concrete evidence of him kicking this ie counselling, prove he has really closed his betting account etc.
Good luck, i know how awful gambling addiction is