Ds is 6.
His attitude/ back chat is awful. I get so frustrated and cross. Every time I ask him something it's eye roll, huffs, has an answer for everything. You tell him not to do something, he does it again straight away. You say you've done it again, and he's adamant he didn't or it was an accident. You say it wasn't, he says it was, it goes on. Obviously I stop in the end, otherwise we're just arguing. You ask him to do something, he ignores you. You ask again, he ignores you. You start to raise your voice and you get a growl of 'for gods sake I'm doing it!! Yet wasn't doing it and still isn't doing it. He won't accept he's wrong ever, and won't just apologise and make it right. He makes it worse by upping the stroppy, rude, attitude which then makes me even more cross. I shout. I storm out the room. My behaviour becomes unacceptable. I feel like I've failed and I don't know how to fix things.
How the hell do you deal with disrespect, rudeness etc. I was expecting it in teenage years but not yet. Not at 6. I wouldn't have dreamt of speaking to my parents like he does.
But then I know I don't help things because I get annoyed and frustrated. How do you keep calm? How do you diffuse thing? How do you get them to show respect and not be rude or argue back? I just feel like it's spiralling out of control. 
Obviously I need to work on how I deal with things and am also going to limit tablet time to 30 mins in the evening if his behaviour has been good in the day but any help or advice would be much appreciated in how I can handle things better and also any tactics to get him to behave better.
Thank you