Prayer for the Strength to save my marriage

I have been with my husband for almost 15 years. We have 3 children together. He's had an alcohol problem and for that he's been in and out of jail for years. Last year he became friends with a girl and all this time I wasn't ok with the friendship because I had the feeling something else was going on. He started not coming home, and getting heavily into drugs. He recently got locked up again and since then I found out that there's a second woman in the picture. He's always denied everything I asked him and kept telling me it was all in my head. A friend arranged for me to meet & talk to one of them and found out he's also been writing her and promising the same things to both of us. This other woman told me that their relationship was all based on drugs and sex. He has really hurt me but I love him so much that I want for him to repent and to change so we can start over and make our marriage work. Please pray for our family to work through this and for him to change and regret what he has done to me.