Frightened & Needing Help

My husband and I adopted a boy from abroad. He is 12 years old. He has been in our home for 15 months. Our adopted son has threatened on multiple occasions to kill me, kill my husband, and kill our dog. (We have no other children.) He is drawn to violence and horror. He speaks often of wanting guns. We have been able to 'cocoon' him so far, so his exposure to violent media and opportunities to get weapons are nil. However his threats of killing continue. Six weeks ago he became extremely suicidal and tried to kill himself in multiple ways. He has been hospitalized since. His desire to hurt his parents is not improving. We realize that in a few years, this boy will be a teenager and able to find weapons through associations with friends. My husband and I do not know what to do. We are an older couple. I am scared. I am also distraught. Our son has many gifts. He is extremely intelligent, charming, makes friends easily, is affectionate, compassionate, and can be most loving in our family. Thus, he appears to have two wildly different personalities. As is true of many adopted children, he has multiple traumas and losses in his past, which would explain the dual personalities. The exhaustion from being threatened with death so many times has taken its toll on me. I am scared, cannot sleep, and cannot function. I am having an emotional breakdown. I feel so alone that it is unbearable. The stress is tearing my marriage apart. My husband is distraught also. Our son has had much therapy with the best therapists. Yet I see no hope for peace. We have reached the difficult decision that we cannot raise him. Our son wants to grow up near his siblings, in his home country. He regrets deeply being adopted. He wants to live near his siblings, who are not adoptable and are in the country from which he came. We believe the best future for him would be to grow up in a trauma-trained family in his home country, or in a trauma-trained family here in the United States. We do not know where to begin. Is there anyone who can help me?