I know entirely how you feel - DDs dad and I were together for 10 years (married for 4) and he had a gambling addiction which extended back to before we got together - obviously I didn't know about it when we got together.
It didn't really faze me until we began living together, and the final demands started to arrive. I personally bailed him out using money my parents had saved since I was a child, and later my parents further bailed him out. Every time were promises to seek help and things would change. I was kept well out of the picture though - we had a joint account which I had no access to, and he dealt with everything from arranging car insurance to paying for prescriptions.
It all came to a head one day when I received a court letter for unpaid council tax and found the passwords for the online banking in his briefcase. He was absolutely haemorraging money, sometimes up to £500 a day and most of the direct debits for bills had been cancelled to fund it. He was on a drunken day out with his friends that day, and I rung him screaming to get home that instant, that I knew everything and wasn't sure I could forgive him this time. By then we had DD so he'd risked the roof over our heads. He cried down the phone and gave yet more excuses, promises and apologies. My darling mother bailed us out again on the agreement that I took over all the finances and he had no access to the bank at all, and was given pocket money each week like a child.
Eventually we split for other reasons - he fucked off with some slapper half his age that he worked with, but I could only feel relief.
We're now more than 2 years post-split and I know he still gambles, but you can't imagine the relief I feel that it's not my problem any more. Every day was full of stress, wondering what letters would come through that day, which debt collector would be on the phone.
Unless he seeks proper help and truly wants to, HE WON'T CHANGE AND IT WON'T STOP. Of that I can absolutely promise you. Sorry you're in this situation but please please consider staying behind and going forwards by yourself. Feel free to PM me if you need any help or want to ask anything :)