3year female long history night terrors&aggressive, violent tantrums. seems very emotional compared to my other kids. should i be concerned?

Possibly: What has your pediatrician told you? Your child should be considered for a sleep study given the severity of her parasomnias.

Yes, medical, : developmental & behavioral health evaluations are needed. Your school district's Child Find can assess for eligibility for Early Childhood Special Education for social/emotional delays. Also, seek referral to a child psychologist & psychiatrist or developmental/behavioral pediatrician. It is vital that the child receive no positive or negative attention from any family member for the tantrums.