Wife with mental illness frequently leaves with the children?

My wife has yet to receive firm diagnosis regarding her condition. She suffers from depression, anxiety, and possibly bi-polar or borderline personality disorders and is on medication. When we met the writing was on the wall. She was in a relationship a few years earlier and cut both arms deep from the bend of the elbow to the wrist leaving very visiable scars. She said her ex trapped her in the bedroom and was hitting her and would not let her out. She thought if he saw the sight of blood he would get scared and leave. I still don't believe this is the full story. Why would you cut both arms? I think she is covering up something. She frequenty lies or does not tell the full truth. When we met she dressed very provocatively, drank and went to bars, and had some questionable friends. I looked past all of this because she was a high school biology teacher, had a masters degree, was very intelligent and came from a good family. She was 37 and I was 39. She was married in her early 20's and has a 19 year old son. I too married early and have a 23 year old son. We both felt short changed as single parents and wanted to start another family and raise children together with a mother and father present full time. We started trying for a child and planned to get married in the near future. The next month she was late with her period and we thought she was pregnant. I was so happy. We still weren't living together full time, she had a house that her brother helped her buy years earlier that we put up for sale. She was planning to come over with a pregnancy test so we could get the results together. She showed up drunk and had her 15 year old son drive her car. I was crushed. If she was pregnant, she shouldn't be drinking. Her son left right away practically dumping her on the front lawn. I told her to get in my car and I would drive her home. Because of this she said I didn't love her and was going to walk home. She lived 20 miles away. She could barely walk she was so drunk. I stayed calm, finally got her in the car and I began to drive. I told her I didn't think this was going to work and she attempted to jump out of the moving car. I dropped her off and waited for a while outside her home in my car to make sure she was OK. I cried the whole time. Next morning at 6AM she was knocking on my front door. I wasn't going to answer but she would not stop. I let her in and she begged me for forgiveness. I did. Things progressed rapidly from there. She got pregnant the next month. Her house sold. I bought a beautiful brand new home. It was perfect. She wanted to give up career and be a stay at home mom. I realized the incredible financial pressure that would put on me, but I agreed. After our son was born post partum depression struck making life worse. The pressure was getting to me. I was growing frustrated with the financial burden, her mental illness, the unstable home life, and lack of sleep with a newborn. She attempted suicide on two occassions. I saved her both times. We both went to counseling together for a few weeks but could not afford to keep going. The economy turned, I received a pay cut at work and I could not sell our home because the prices dropped. I was just scrapping to get by. She got pregnant again. Our daughter was born at 25 weeks, 1lb, 8oz. She was in intensive care for 3 months. We spent a lot time at hospital, we took turns since we had our infant son at home. When I was visiting my daughter one night, she attempted to kill herself again with pills. At times she seems stable, other times not. Our children are doing well, now 2.5 and 1.5 respectively. But life has been a rollercoaster with her. My frustration leads to me lashing out verbally, have even resorted to name calling. This has not helped. She frequently leaves me, nearly on a monthly basis for a week or so to stay with her parents who live an hour and half away. Half the time when I come home from work I don't know if she is going to be there or not. The house is dark. My children are gone. My life is so unstable. She now blames me for everything and said she is done. I'm not perfect but have been totally comitted to being a good husband, father, and provider. I've given up all outside activities to be with my family. I come straight home from work everyday. It's all about family values for me. It seem when she is away she goes back to that provocative style of dress. I wonder what she is up to? It seems she is circling back to the way she was before we met. I just keep putting up with her behaviors and feel walked all over. I dont want to give up, but I don't know what to do. I miss my children. As far as I know she is still taking her meds. She does not talk openly with her Dr. Her family blames me. What to do?