You can file the following cases against him for relief and remedy to all the problems you face now because of him:
1. You can lodge a criminal complaint with the local police for the offences under section 406, 417, 420, 498A, 294B, 323, 503 and 506 (ii), IPC against him for marrying you by suppressing the fact of his subsisting marriage with another lady at the time of marrying you, for breach of trust, cheating, for the acts of cruelty, for injuring you by assault and criminal intimidation etc and also for protection from his threats to kill you and your child.
2. File a DV case seeking protection, monthly maintenance for you and your child, compensation for his arrogant and atrocities committed on you during your stay with him, causing acts of cruelties when you came to know about his subsisting marriage before marrying you and also for residential rights.
3. File a contested divorce case on the grounds of cruelty and also for suppressing the material facts of his subsisting marriage at the time of fraudulently marrying.
4. File a maintenance case under section 125 cr.p.c. seeking monthly maintenance for you and your child.
You need not file a child custody case since the child is under your care and custody, he cannot take away the child because as per law the child shall remain in the care and custody of the mother till it attains 5 years of age.,