Succession of property and death certificate

Dear Sir/Madam, My husband died a week ago. We have no information of what assets/properties/bank accounts he had. Even his death certificate is with his elder brother who is refusing to hand it over to me. In fact he is pressurising me and my two kids (son 29 year old but mentally not well and daughter 24 year old) to sign Power of Attorney to him stating that there are lots of property on joint names but attached by bank against some business loan hence he has to fight court case jointly. We are living in absolute deprived condition since last 12 years. My house was also attached by bank approx four years ago and we were forced to vacate with a notice of literally 30 mins by the bank. Initially I lived with my parents in different town for three months and later moved back with my husband renting a small apartment. We do not have money even to eat food twice a day. What shall I do? Shall I trust my husband's elder brother and sign the power of attorney? Would he deprive me of any assets or he really needs to fight court case. Even this court case is going on since last 15 years. My husband's brother is living luxury life even though by husband was equal partner. They had big business but all lost. I am unable to understand why my husband's brother is rich and we dont even have food to eat even when both were equal partners. Please advise 1) How do i get hold of death certificate 2) Shall I sign the power of attorney to my husband's brother? 3) Would I lose right to my husband's properties once i sign the power of attorney to my husband's brother? Thx M.A.