Why are Indian Muslims (& Indians in general) so insecure about Pakistan, & their roots to it?

My mother is from Hyderabad, India & my father is from Karachi, Pakistan & I'm American. I consider myself as a neutral in this matter. Indians Muslims live under fear of a siege, they always have to keep proving their nationalism to their communities & India, that they have no connection to Pakistan. They are insecure of their Muslim (& more specifically Pakistani) roots. They always have to apologize for Muslim attacks in India, but they cannot speak loudly against violence against them. Why is India the country so insecure about Pakistan, & why do Indian Muslims have to 'feign' a hatred towards Pakistan? I have been to Pakistan before twice, & I have not been treated differently there: people are more secure about themselves.