Getting custody and moving out of state

I want to divorce my husband and move back to Indiana. I have always stayed at home with my daughter and been the primary caregiver since her birth. Although I will have to go back to work, living in Indiana would allow me to avoid daycare since she could stay with my parents after school (they are self employed). We also own a second residence in Indiana that I would want to live in. I want very few of our marital assets, mainly just my car, our Indiana residence, and some personal items. I could care less about the business, our property here, or any other assets we own. I just want to start over with my daughter. I'm praying that my husband will be reasonable once I tell him I want a divorce, but I am a little scared that he will attempt to fight me for custody since I want to move out of state. I want my daughter to start kindergarten in the fall in Indiana. I will definitely be able to provide a more stable home environment for our daughter, as I am an accountant and he owns food concession stands that require extensive travel in order to make a living. Although my family lives in Indiana, my daughter and I have spent a lot of time there over the years so it wouldn't be a completely foreign environment to her. Although we would live far apart, I would want to do everything possible to make sure he gets to spend time with her as much as possible. His work would allow him to come to visit her in Indiana in addition to a typical out of state visitation schedule, and I would encourage it. Our daughter is used to him being gone a large amount of time now and is used to being with me every day.

My question is this: What are my chances of being able to get custody and move to Indiana if he decides to fight me?

Here's some basic background info on my situation:
Background:
?   In June of 2001, my husband decided that he wanted a relationship with another woman. He told me about it, but also that if I didn?t agree he was going to do it anyway. He essentially coerced me (emotionally) to be involved in a threesome with them, which lasted from July to August of 2001. I then refused to be a part of it.
?   December of 2001, we went to Indiana. He led me to believe that his physical relationship with her was over. In June of 2002, I found out that it had never stopped. She moved in with us.
?   When she moved in with us in 2002, he decided that he was a polygamist and that the bible says it?s ok, even if our laws don?t. He considers her to be his second wife and supports her as if he was her husband.
?   January 2004 I found out I was pregnant. When she found out, she moved out. He begged her to come back, and when I objected, he told me he would leave me if I didn?t agree. Being pregnant for the first time, I was scared and gave in.
?   I spent the summer of 2008 at my parents? in Indiana while working on my Masters degree. He was travelling constantly in the North that summer, from the East coast to the Midwest. He had stopped to see us for 2 days and she was not happy about it. She insisted on being taken to a hotel instead of staying in the camper on my parents' property. (We were staying in my parent?s house). I objected to his taking her to town and paying for a room in the short time he had to spend with his daughter, he called our marriage a farce and took her to a hotel anyway.
?   In November of 2008, she moved out of our house because she was upset that my parents were coming to visit at Christmas. They didn?t know about his relationship with her, so she was upset that she would not be acknowledged as anything other than a friend during their stay. At that time, my daughter was upset that she had moved out. My daughter adjusted to it over the following week or two and I refused to ?allow? her to move back in. I didn?t feel it was fair to my daughter to have the upheaval involved with their issues.
?   In February 2009, he moved her into a travel trailer in our yard. He didn?t tell me about it until after she had started moving in.
?   Our business requires him to travel in order to work. She works with him, and they are out of town a lot. They were gone for 80 days from July ? December 2009. This is a typical schedule.