Seeking permanent custody of my son

My name is Edith  I am the mother of three children, my husband and I have one child together and he is the step father of my other two children. We have been married for seven years and went through two deployments. Our son that we have together, Jimmy whom is four years old who has severe medical issues due to asthma has been hospitalized multiple times because of this condition. On December 3rd, 2013 my husband was deployed to Iraq in which we were fully prepared for even with only having a three weeks’ notice. During this deployment I started to notice that my husband began to call and email less in which I thought nothing of it because of the stress and workload of his duties. My husband called me one night  and told me  he wanted a divorce and  then hung up. Distraught about what had just happened out of nowhere. About 7-10 days later I received a call from my husband and he began to apologize and tell me that all of this was a misunderstanding. As soon as we made peace about the situation the emailing and phone calls between us started back up and we began to work things out. When that day came I and my three children were there to greet my husband; which was at the beginning of June.  The time he got off the plane did not speak to me or his step children, nor did he show any affection towards me and told me “I am not coming home with you”, gave our son Jimmy a kiss and walked away.  He left with another female solider and I thought nothing of it. I went home and after a week of him being home nothing. No calls, no text, he didn’t come by to see the kids. I did not know where he was living, had no contact information for him. I was left stranded. I started getting worried mainly because of finances. We share one bank account and one debit card with his name on the account only. I didn’t have any access to the money to provide for our child. Four days later he came home to see our kids finally and never left. He acted like nothing had happened and began a normal routine at home with our family. He told me that he had a lot going on and it was a little overwhelming and he wanted nothing more than to make our relationship work. I asked him where he had been living for the past 12 days and he informed me it was a fellow male solider in his unit and he rented a room from him. At this time I was so confused but all I wanted was to sort everything out and for our family to be together.Came home to find my husband home on the porch where he began to tell that he is in love with somebody else and while I was gone he had went to the beach with another woman and our son in Wilmington. He would not tell me who and I told him that if that’s how he felt he needed gather his belongings and he needed to leave. He goes inside the home where I see my son suffering from a severe asthma attack. I give him a treatment, while me and my husband are talking back and forth which I have on recording where I am asking him to leave and he gets physical; Within seconds my husband , pulls his gun out waving back and forth and presumed to tell me that “He is going to end all of this now”. I call the neighbor to get my son she comes and asks no question and leaves with him. I told him that he could not take our car because of the condition my son was in. He loaded his gun in front of me and left and started walking down the street.  When he left I went through the car and found cigarette ashes all over and a backpack. Inside the backpack were cards from a female  he was cheating with.The following day I went to his unit and informed them that he is committing infidelity, he had threatened me with a gun, and that he had left me with no money. . I told them about the current situation about the gun, having no money and his infidelities. I also gave them the cards that the female sent to my husband. They put in a temporary 7 day restraining order and I was informed they would do their own investigation and get back with me.  Nothing ever happen . Even though the Army instructed Jimmy to pay the house mortgage, he hasn’t, and the house is
currently in foreclosure. In July, Jimmy did a voluntary re-possession on our only vehicle because
he said he was buying a motorcycle instead and couldn’t afford both payments. He has continuously
refused to give me a copy of his LES (military leave and earning statement) so that I could seek
daycare or pre-school for little Jimmy while I seek employment. The LES is also needed to
potentially receive benefits from NACCAR and apply for WIC benefits. In addition, my son
must remain on medical insurance due to his asthma condition.
I can’t financial higher an attorney. Went to legal aid and they don’t take on these type of cases. I have been his full time mom and dad. For him ask for custody. Over 5 mts he has  only seen our son 4 times. When he see dad he decides not to give him his medication not sure if it laziness or forgets. The Dr. did wrote a letter to the court about this. It is so sad that someone could act so selfish that he would put his wants above the needs of his son.  He is living only 10 min away. He has threatened me that if I leave the state he will file child abduction charges on me. I have nowhere to go. My mother is already living with 5 other family members in Arizona. Not only that but it is clear I do not even have the financial means to even think about leaving.  I have even gone to the extent of going to the Chaplain to receive commissary vouchers to provide food for my children.    I currently have no employment and he never allowed my name to be put on the bank account so I have no access to money.
And all he want's is to take our son from me. Please help!!! I am humiliated and Embarrassment to even ask for help.