Please give me the strength.... 🙏🏻

Temporarily living with my mom for the past few months and will be moving in 2 weeks across country. I’m currently 4 months pregnant and I have had zero patience for my 8 year old nephew. He has a terrible attitude, extremely rude and is very greedy when it comes to my 4 year old. I want so bad to scream at him, but I refrain myself but what upsets me is that my sister or his parents doesn’t do enough to discipline him. He curses at my daughter, takes her things and hides her stuff, then plays the victim. I know majority of each pregnancy there’s that one person that just irritates your soul where even if they don’t do anything, just in your presence alone irritates you, well I’m feeling that way. Please give me some words of encouragement because I would really like to be petty and pull him aside and tell him how much I dislike him. But I know that’s not the right thing. I’m trying my best to ignore him, but he barges in my room and it’s difficult to avoid someone when you live with them. Ive told my sister how much he upsets me but totally understandable that she’s oblivious to his horrible behavior to others. 2 more weeks cannot come any sooner.. how do you cope?