Shlok is basically saying that Astha should not have direclty confronted Aditi in front of everybody, she got the proof destroyed and got her image spoiled in front of everybody.
His dialogues are very sensible actually..except that he told her Farak nahi padta at the end...that is extra special Shlok dose.
Shlok is not saying that Astha lied or that he does not trust Astha. He is saying she should not have dealt with this matter in this way.Also Shlok probably knows that Aditi was trying to hurt Astha just as a means to take revenge on Shlok. He is Aditi's target not AStha. And our AStha does not know that.
I think Shlok knows Aditi is related to all these accidents and has been noting these things since Holi. But he is not over reacting like Astha , because he knows there is a purpose why NA brought Aditi here, and bigger problem is NA not Aditi.
Also Anjali though is protecting Aditi...Anjali got a big clue today when Aditi raised the Sui-Dhaga incident...where Astha comes to Anjali to learn putting a button on shirt.
By that Anjali will understand two things. Aditi tried to come so close to Shlok as to try sewing his shirt!!.
And that when Astha was learning from Anjali...Aditi was watching.
Anjali actually suspected Aditi from the beginning...especially after the fevicol and vinegar incident.
Both Anjali and Shlok are protecting Astha by making Aditi feel that they trust her. This will come out in the future. Anjali is very worried because if NA comes to know family suspects Aditi then he will up his strategies even more.
My POV. Of course they will not show us Shlok outright taking AStha's side right now...because this point will be used for AStha to stay back or leave depending on the rift caused.