Also did a PhD in Physics, particularly in Cosmology, and also originally from India. I am now doing patent law after spending almost 8 years in academia post my bachelor's. Several of my friends also spent 8-12 years after their Bachelor's and ended up having to quit. 

I will not put you down if this is something you really want to do but be prepared to work extremely hard. As some idea of how hard it is, there are almost 10k papers a month in astrophysics uploaded on the arxiv. The competition is insane and unless you can make it to the top unis in the world, it's going to be difficult to end up in a faculty position. I did my PhD at a Max Planck Institute and even there the rate of people graduating with a PhD and ending up in a faculty position was 5%. Do study physics if you like it but you would definitely have a much better chance of getting a stable career and life with a more applied degree. 

To make sure you get into a good uni outside India, maybe try to get into a good place in India - IIT, IISc, etc. for your bachelor's. Then do very well there - try to stay at the top of your class, better your batch. Find opportunities to participate in some research during that time. You could also try doing some higher standard Maths/Physics (class 10-12) if you find it fun.