Here comes My Take...
According to me he is 50-50 Justified...First of all...Zoya shouldn't have go there...even if she is going..what was the point of taking Najma with her? Asad clearly said He doesnt want Najma to go..still zoya did this...Ok Fine u want to go..but u just cant take najma with u...asad is over protective about najma..she knows..but she still did this...by doing this she disrespect Asad's decision... actually I think Because of zoya Najma is going away from Asad...najma started lying, started hiding things from asad..which she never did before...so practically zoya ruining najma... u r living in Asad's house..atleast show some respect... so i think asad's gussa is justified...
Now comes another thing..that Asad shouldnt have talk about Zoya's parents..may be he doesnt know Her pain and all..but still he should have do that..normal scolding was fine...But i hope he will realise his mistake when he will get to know that Zoya has a bitter past too...