All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
You should know that the brotherhood between yourselves is of far greater importance than have it spoilt by a temporary worldly pleasure. Kinship is of great importance, so one has to be keen on keeping good relations with family and be cautious about anything that could spoil them. In addition, there is brotherhood in Islam, which then makes kinship more confirmed, and cutting relations is more abominable. There is nothing in what you have stated that makes your brother responsible for your money. The fact that he advised you and you accepted his advice does not necessarily make him responsible, and you should not reproach him, as you have stated that he lost some money too. So you should not hold him responsible and he is not obliged to pay any money to you. Therefore, it is not permissible for you to cut relations with him, as there is no reason for cutting relations with him. The Prophet said: "It is not permissible for a Muslim to cut relations with his fellow Muslim brother more than three days." [Al-Bukhari and Muslim]. A severe threat has been reported in this regard. The Prophet said: "The doors of Paradise open on Mondays and Thursdays; every servant that does not associate anything to Allaah will be forgiven, except a man who has enmity towards his Muslim brother, and Allaah says: ''Leave them until they reconcile, leave them until they reconcile, leave them until they reconcile." [Muslim] You should know that this is a test for you, so you should be patient. Generally the outcome of patience is good. If you find that man you could ask him for the money if he had expressed that he will be a guarantor. Finally, we draw your attention that life insurance is prohibited, and it is not permissible for the heirs of a believer to take this insurance except the instalments that he had already paid to this insurance company.
Allaah knows best.