If my husband is in prison, will I get sole custody when I file for divorce?

I have been married 8 years. Last 2 years he has been in prison in another state. Since he's far away my children Have seen him maybe 5 times in the last 2 years. He has at least 2 years left since its federal time. I plan to file for divorce, things with us aren't great obviously and before he left things were bad. When he left my children were 5 & 1 so with my oldest he would have missed half her life and my youngest almost all of it. He's been sentenced for trafficking meth. When I divorce him how likely will it be for me to have sole custody and possibly terminate his rights. I plan to move out of our home state soon and let my children start over elsewhere, after the divorce is final.