welcome to SR. I stumbled upon it 6 years ago and count it among my greatest blessings. Loving a person with a substance abuse problem is past difficult. And when it is compounded by children it's really hard.
My perspective is that your daughter REALLY needs you. Way more than your wife. You are your child's sober parent and she will need you to be 100% able to raise her. In recovery, detachment with love is the recommended approach to dealing with loved ones. It is appropriate to be compassionate but absolutely you must think about yourself and your daughter first. I've always heard that if you raise a child with an addict in the home you are either teaching the child how to be a user or tolerate a user. Neither is healthy.
You don't have to close the door on your wife if you don't want to but it makes sense to stand back while she learns to deal with her issues. Unfortunately, it is a journey that a person really has to take alone. I would ask myself if I would be able to forgive myself in something happened to my child is I left her with someone that might zone out (or worse) due to drugs. Addiction is a lifelong disease and all any addict ever has is a daily reprieve. Using a drug is not the only problem - the real problem is a difficulty in living life on life's terms. It just takes a long time to change old patterns, learn new behaviors, and to be sober.
When you are involved with an addict you get as sick as they are....it means that you have to work your own recovery program. The good thing is that you will find wonderful people and you don't have to do it alone.
I hope that you will continue to come back as you deal with all of this....