How Can I Get Help for My Fiance Who Has a Drug Addiction?

My fiance and I have a little girl who’s 10 months old, and I’m 5 months pregnant. My fiance is addicted to painkillers and it’s taking all of our money. He won’t admit that he has a problem and we constantly fight about whether or not I got him an extra to hide away for him, or how many we actually had. Spending all of our money on them has put us behind on all our bills and my credit is ruined. We fight about it all the time and it’s tearing us apart. He’s always saying that I cause him to take all of the pills. He keeps promising to detox off of them, and then he won’t get a job or something and he takes 4 or 5 at a time. He’s threatening to leave because he said I lied to him about how many I had, when I gave them all to him. I don’t want our family to be broken apart. Please help me. I love him and our little family so much I can’t even think about losing them without crying. I just want him to be ok.