One of the things that I learned that I could not deal with is the realization that addiction really is life long. No point in cherry coating that, it is. There is a chance a person can relapse 20 years later, you just don't know. Recovery from addiction is a long process. She has to be willing to work on this every single day for the rest of her life.
If she was at that stage of addiction, 7 months is not very long. Not that she cannot or won't recover, there are people who definitely do. It's only up to her and how committed she truly is to her self and her own recovery. If she is only doing it to buy more time to get you to agree not to divorce, relapse is likely.
Counseling with a counselor who is familiar with addiction issues (if not, don't waste your time), would really help. It was a God send to me. It made me realize that no matter what would happen with my marriage, that I would be able to stand on my own two feet and get through it.
Keep reading. Read all the stickies at the top of the forum, they have wonderful info. Keep posting. You are not alone, there are many here who have walked in your same shoes.
Welcome to the forum.