Hi baxter,
Just wanted to add my two cents along with everyone elses. You are NOT a bad mother.
My advice for anyone is "Don't ever get married, don't ever have kids." I picked the wrong man to marry and had two kids with him. We eventually divorced and I was left raising our kids except for his meddling when it didn't help. My oldest (son) is the addict and my second (daughter) is a head strong, know it all, who is always right. I've always gotten along well w/my son, but he makes my heart hurt - he is super sensitive. My daughter, who I currently live with, has been a struggle to get along with since the day she was born (so I know how you have struggled.)
I fantasize about running away from home - shouldn't that be the kids??? And hope to one day be on my own. (My daughter just started a 2 yr. nursing program. I hope we'll both go our own directions after she graduates.) Anyway . . . you are not a bad mother. Take care of yourself as best you can.