Dear Aanchal,
I’m so sorry you’re having to go through this. You would think that this day in age we would be past such prejudices, but unfortunately they still persist in some people’s minds. Honestly, we have more in common than we have differences. We all yearn to be loved for example. It’s also equally troubling since most religions (I assume he’s Theravadan Buddhist if he’s Sri Lankan) teach tolerance and say nothing in their sacred writings about “don’t marry someone from a different country or a different faith”. (Full disclosure, I attend a Theravadan Buddhist temple, so I’m pretty familiar with their beliefs. There are a few mixed race couples in the sangha, and no one pays it any mind.)
It’s equally sad that your beloved isn’t brave enough to defy his parents. Sadly, until he’s ready to work up the courage to break free, there’s nothing you can do. Perhaps he may eventually come around, but in the meantime it may be best for you to start the process of healing.
I wish you the best, and that you find a man who will put you first, even if you are of a different nationality or faith!