Boyfriend addicted to gambling

Okay guys what do you do when your other half has a gambling problem but won't admit it? Won't go to therapy ect. My boyfriend has always been bad with money, then it got to the point he would get a red-letter every week. It ended up he owed about three thousand through various things and he was taking the money I gave him for bills and using it for something else. He would lie to me and say the huge bill we got was a mistake but sure enough when I phoned up he'd not been paying. So I helped him pay off all his debts and everything seemed okay for a while. Then he got a credit card (I did try to get him not to🙄) at first he would pay it off but the last few days he's been constantly asking if we have post. Another credit card just arrived this morning which I'm guessing means he maxed out the first one. When I mentioned this to my sister she said that he's been spending hundreds online gambling while on his break at work but she wasn't sure how to tell me. We have three kids together and I'm tired of never being able to get them nice things because I have to foot the bill all the time.