Divorce Advice for Men | Fathers Rights Divorce | Child Custody

I am in my mid-twenties and in the military. I haven't been deployed ever and have served for over 6 years. I married my wife because she was pregnant and we now have two children. She has a history of suicide attempts, alcoholism, and she cannot hold a job. Another thing that bothers me is that she smokes in her car. When I fuss at her about it she says that the girls don't ride in there much. Granted the girls aren't in there at the time but they do ride in there afterwards. She recently quit a job making good money and has left us high and dry and now I am planning on divorce as this has happened too many times. The problem is that I am scared of losing my girls (2 and 3 years old). I would almost rather stay with her and be miserable than leave and be miserable without my children. Do I have a chance of getting my girls? She is not close with her family and will not move back to be near them, but I have a lot of family close to my base and my girls love their grandparents. Also, I stay at home with the girls after work and I was the only one home with the girls on the weekends when she did work. When she would get home on Monday and Thursday nights, she would ignore me and the kids so she could go out. Since she has quit her job, she claims she won't be going out and drinking anymore, but I have heard this in the past. Can you give me any advice?