Well we learned the lesson & don't sponsor terrorism in the neighborhood any more & nope a great power always involves itself in the Internal affairs of it's neighbors to safeguard it's interest
India does hold the mantle of being the largest nation in South Asia. It would benefit you guys to have a less interventionist policy with your neighbors such as Sri Lanka, Nepal, Bangladesh and Pakistan.
Take for example Japan and China. You think Pakistan and India have it bad? SIno-Japanese Wars led to the deaths of millions , unprecedented destruction in both nations. Yet, despite it all, Japan and China have risen above our past and have developed together, integrated and have a bilateral trade that is the largest in all of Asia. Our bilateral trade is close to $400 Billion per annum. Unprecedented bilateral tourism (5 million Chinese tourists [PRC + Taiwanese] visit Japan a year ; and over 5 million Japanese visit China per year. Tho China and Japan have maritime disagreements, we have mechanisms set in place to prevent clashes. We both also have non-interventionist policies regarding each other.
South Asia, in general, can learn from the successes of China and Japan.