6 year old behavioural issues

[mush23]

My daughter has always been an anxious child, eager to please and quite clever. Shes got slight hearing problems, she finds it difficult to hear and loud noises overwhelm her (she hates fireworks, thunder and ambulances etc). Her bother was born 3 months ago, we made a conscious effort to include her in everything and explained the process of mummy going in to hospital for a short time. We made sure she met the baby before anyone else and was alone with us as a new family of 4. We make an effort to spend one on one time with her aswell as including her with baby related things (bath time, she helps make bottles etc) she very much loves her brother and I'm confident she would never hurt him. However her behaviour towards us is alarming. She has tantrums like I've never seen, she screams hysterically to the point of losing her voice, she swears and says she hates us and would rather live with someone else.
We've tried everything to curb this behaviour, ignoring her make her scream louder, shouting at her makes her fight back I've threatened to send her to live with her grandmother as this behaviour is making me ill. She throws her toys around and destroys her room, then refuses to tidy up, threats to throw her things away lead to her just sitting there saying ok. I've even tried holding her and giving her a safe space but that lead to me being bitten (she had never bitten anyone). I've even found out shes lying to other people about the way she is treated. She had told my mum that shes left alone all day, I forget to feed her and I ignore her in favour of her brother, I had to explain to my mum that this is all untrue, the poor baby spends more time in his bouncer than in my arms, I try to play with her and she just screams at me to leave her alone, and I have never forgotten to feed her. Granted I have asked her to wait for things as I am feeding the baby or changing him but this is few and far between.
Her behaviour has reach a point of concern where my DH is convinced she is mentally ill, today he became so frustrated he cried (in 13 years I've seen him cry a small handful of time so it's safe to say he isnt a teary person)
Does anyone have any advice to offer?
She isnt like this at school or with anyone else so I feel like I cant reach out to teacher or other family members for advice

 

[Scout]

I recently spoke to a child therapist about my daughter's issues (hitting herself and repeatedly slamming a door on her hand when upset, calling herself all kinds of awful names when angry) and she suggested play therapy to help her learn how to cope with, what she calls, big emotions. I feel so much relief knowing she has someone she can talk with who knows about these things. It has taken a weight off. I don't know if it's something you'd be comfortable doing, but it may be worth speaking to someone who's knowledgeable about child development and issues to seek their advice. It sounds like you are doing everything you can, and it's apparently not what she needs, but at 6 they can't exactly tell you, you know. Idk, I just feel for you. I know how awful it feels to know some;thing is going on and you try everything you can to 'fix' it, and it's not working. That was my whole summer before I finally decided to speak to a therapist. Good luck and hope things with your little one get better.

Oh, wanted to add: my dd's behavior is good at school and it was only at home (where she feels safe) that she was acting out so much. I still spoke with her school counselor and let them know what was going on so they could let me know if they saw anything at school that I might need to know. Also, the school's counselor said she'd make herself known to dd, so she'd have someone to talk to at school if she ever needed. This is always confidential, so her teacher and all other staff are not told.