Can someone help me explain this part of B**ds of Bollywood?

I am late but I recently finished watching The B**ds of Bollywood. I am very confused about one part.

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So in the end it shown that Ajay and Neeta had an affair which makes Aasmaan Ajay's son. Then it was shown that Ajay and Neeta were communicating with hopes that the film shouldn't happen as Aasmaan and Karishma are half-siblings. So I wanted to know if Ajay knew before hand that Aasmaan is his son? Or even he found out that time only?

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If Ajay knew that Aasmaan was his son, why was he so brutal towards him? No father would attack their son that way. Unless he doesn't think of him as his son.

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I am confused because earlier it was shown that Ajay didn't want Aasmaan to work with Karishma because of his status, but the ending is showing that he is against only because they are half-siblings, but his actions were so brutal.

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So if someone can clear this for me that would be great.