really struggling with DD (7)

[rhetorician]

she was recently diagnosed with dyspraxia and some sensory stuff, and for the most part manages well. But I am really struggling with her behaviour at home which is rude, ungrateful and full of aggression (verbal mostly). In particular, she does things like try to make a den for the cat (who is 14 and very forbearing, but really not into it) and then gets angry when the cat won't do as she wants. When I tell her off she gets all aggressive, refuses to listen, and says things like "you like the cat more than you like me", because I won't let her mistreat the cat. I have just told her in no uncertain terms that she needs to sort out her behaviour and she is upstairs crying. If I even slightly raise my voice she stomps off complaining that I am being "angry" with her. I am really concerned about her response to being disciplined, and to her complete unwillingness to back off when asked, let alone when this is signalled more subtly. Ideas?

She may be coming across as aggressive and defiant, but saying "you like the cat more than you like me" seems to me to indicate a sad, insecure child rather than a naughty one. Do you think she is struggling to cope with the diagnosis more than you realise?

she doesn't really know about the diagnosis as such - but yes, this is all insecurity - it might have something to do with the fact that I am going away for a week tomorrow. But I just don't know how to make her feel secure and happy - she sometimes makes mistakes because she is 7 and isn't the best at social situation, but I have to be able to tell her off!