I think his sister is evil and a hypocrite because she copied Mustafa seal and she also caused his death so she killed two of her brother's she is kind of crazy like her aunts
No she's not. This is a show but even then what she did protected her brothers including Selim. Not that it was right but blame the writers for taking creative license.
He knew Süleyman was going to k*ll Mustafa but he didn't stop him. He took Cihangir away from the camp knowing Mustafa would be executed. But in fact he couldn't have stopped his father anyways. If Süleyman and Hürrem wanted to k*ll they k*lled. But they all paid in the end. And not to forget Mirimah and Rüstem who helped Hürrem to plot his death.