Attachment..HELPPPP

My daughter is almost 3 and she cannot be in a room in our apt alone unless her dad or I are in the room... we can’t even go to the bathroom because she’s scared to be alone in the living room... even if we put all her toys out there and have cartoons on... and the bathroom is right across from the livingroom... her dad thinks i baby her.. but she’s always been like this with me , has been on me since born... I try to talk to her but still is scared.. I have another daughter 9 months and I’ll tell my oldest to stay with her just so I Can go to the bathroom or kitchen quick and nope she won’t... how to I get her not to be so scared??? And be more independent..