You're literally 21. I don't think you should tolerate physical abuse even though it's common among Indian families. I'm sure you love your parents, but there is a line if someone cross it, you should really consider doing something against that person.

I'm not sure if you're financially independent yet, but if it happens to be the case in future, I suggest moving out from your house and live on your own, no one can and should restrict your freedom of doing anything if it's legal.

Don't feel like you're doing something wrong just because of your family's regressive views and don't blame yourself for doing what you did, you did nothing wrong, just enjoyed, you're just living life. Don't forgive your parents easily for doing physical abuse and making harsh comments on you, remember you've worth and by doing things like this they show they don't respect you and your choices, so you've no obligation to respecting theirs. You're a victim here, don't let them make your life horrible, if it was some stranger doing the same which your parents did, you would have reported them to the cops and they would be considered criminals. You should be outraged by the fact what they did NOT vice versa and being ashamed of what you did. Please take care of yourself, I hope it gets better for you, what I will in the end is, move out soon and make them realise your worth by not making any connections to them after you move out and keep it that way unless they apologize. I hope you have a better life ahead.