Why are you dismissing real intelligence, and repeated confirmations even from intelligence services from outside India. You can never have 100% proof because to get it, you need your own law enforcement to help gather the proof. No outside country can give you it all sitting outside your country. Your agencies have to be responsive.
You are real victims of these terrorists, surely you must have taken a moment to say, " Wait a minute, time and time again we have gone down the wrong path, time and time again we have trusted blindly that surely we are not harbouring dangerous characters". How difficult would it for you to try something different and say " Too many people, countries and sources are pointing in our direction". As victims of these terror acts, we must at minimum make sure for the love of our country- that we eliminate the strategy of harbouring such people".