Teenage Boy seeking custody of son

[get_my_son _back9_20]

My son is 17 years old and has a 6 month son with his ex-girlfriend.  The ex-girlfriend is no longer allowing my son to see his baby.  She has married and her new husband has joined the Army.  He is to go into basic training in June.  We need help now before it's too late and she takes him away!!!!!