War does not prove which side is right or wrong; it only proves which side is stronger (with due apologies to Bertrand Russell). And India is way stronger and can defeat Pakistan quite easily. But both countries will suffer immensely, in human lives and in human suffering.
Moreover war will not achieve much. It will destroy Pakistan, which is already in a bad shape economically.
More of Pakistani youth will turn to terrorism as a career. Pakistan's state sponsored terrorism will become a full time business.
What India needs to do is to identify terrorist camps, hideouts and sympathizers and destroy them indiscriminately, like Israel does... even if it involves collateral damage. If that leads to war, so be it. But first give peace a chance. Target the terrorists relentlessly.