Allison......I don't know if you are thinking straight here. IF he has custody of the children, you WILL be paying child support, depending on how much you are making money wise. I doubt he and his mom are going to give you anything but visitation, even in the long run. And visitation is going to be difficult if you are 8 hours away. So, you will be sending him and his mom five, six, seven, or eight hundred dollars a month, or more each and every month for the care of your children you hardly see. And this will go on for years as the children are still young. So, unless you have thought long and hard about this, don't jump into anything.
Also, you are VERY stressed and feel boxed into a corner, and see no way out. And, your reasoning ability may be not what it usually is. Now, you are being shown a light at the end of the tunnel and it probably seems like a savior to you....follow the light and you will get out of this mess. HOWEVER, when you get out, it may not be anything like what you thought it would be. Your little ones will be eight hours away, ........and not just for a night or two or a week or two.....but for EVERY day .....day after day, and month after month......maybe until they are 18. So, please think about this.........the child support you WILL pay, and the fact that you will not have them in you life.
Someone on the board said that this is a common situation right now.....and it is. There are organizations that can and will help women like you in your situation....you just have to find them. Call your local Department of Health or that department in your closest large city or town. They usually have a list of organizations that will help women such as those in your situation. Also try the Catholic church. They also should have a list of organizations that offer help. Even your local town hall may be a resource, also division of family and youth services.
You need to have him pay child support, like yesterday....go to the courthouse and do this immediately.