I think we are failing as a parent

Our 4 year old son cries alot, throws tantrums alot. He doesn't listens to us, keeps waking up in the middle of the night and cries out loud. Doesn't even eat. He does exactly opposite to what we say. Sometimes I get frustrated and yell at him. I am feeling hopeless

Edit: so everyone told me that I need to post more info. So the thing is, he does this only for few weeks. Most of the time he behaves lovingly. He plays with his cousins and seems very happy with them. I have a nephew he is happy with him, but my nephew doesn't like when someone takes his things. And he intentionally takes his things and brings them to me in order to irritate him, so in consequence, gets slapped by his 4 year old cousin. I always try to bring same toys as of my nephew for him too, but he doesn't care. He only wants to irritate him (but 90% of the they both remain happy, he only does this 10% of the time). And one more thing, he only likes boys not girls :D and I am concerned for our new born girl.

He tells us to "shut up and go away" whenever he is angry. He loves us though, because if we give him some spaces, he tries to get our affection again. But he eats very less. Big thing is, I gave him a ipad, so he eats while watching YouTube.

The big change is: my wife recently got a job of government teacher so they both live away from me.