What can I do to have our child custody agreement modified?

I have currently been separated since October 8,2014. I informed my husband that I wanted a divorce after a weekend getaway with a girlfriend where I was introduced to another male. No interactions occurred. However, my husband moved out the next weekend and took everything in our home. He also drained our joint bank accounts and left me with no money and bills due. The house was not in his name and he was not concerned. He used our personal savings to hire an attorney and serve me with temporary custody papers and later on a custody agreement before the hearing date. He told me that if I signed the joint custody papers, he would sign the contract on the house. If I did not sign them that day, he would refuse to sign to sell the house because his name was on the deed. I signed the papers. However, they say that my son cannot be around my boyfriend for 10 months or I cannot move 30 miles from the area. However, I have been offered a job at a growing hospital and it is 65 miles away which also puts me in a different state. We live 8 miles from the state line. The area is where my boyfriend is located as well. My son is asking to come live with me because his dad works 8 AM -7 PM Monday-Friday and 9 AM -4 PM on Saturdays. My son is used to me being his primary caretaker since birth. What can I do to modify this issue when I was blackmailed and did not have an attorney at the time?