Cut, cut, cut. I am Indian and would strongly advise you to drop the person immediately like a hot potato. No need to respond to his inappropriate questions. No need to maintain any further communication with him. No need to tell him you are cutting him off. No need to give him any explanation. I never tell anybody that I am even cutting them off from communication, but I will stop interacting with them if they make me uncomfortable. In my experience, the cutting itself would be your best response and explanation, based on your perceptions and your stated goal:
I don't know if these questions offended me, but it definitely made me uncomfortable (...) The thing is I let it pass because I didn't know how else to react since I have never been in this situation before.
I think it was inappropriate of him to ask me things like that, but I still kept mum (...)
Goal: I would like to cut things off right then and there. But in a way that he won't get offended
In the poor, stupid person's partial defence, thousands of people (including some famous people and humble myself) have sent uncharacteristic/ controversial text messages because of the disinhibiting effect of text/ online communication, even when one actually knows the other person in the 'real world'. However, you don't have to suffer the psychological effects of his disinhibition. So you have already made a good start with
after that I started ignoring the messages.
Go further by erasing his whatsapp number and unfriending him on facebook. Remove his telephone number from your contact list and never reply to his messages even if he tries to provoke you with more nonsense statements or Indian type of sentiments. Perfect silence is the best reaction to this type of behavior. He can get offended if he wants to, but you are definitely not telling him anything rude or impolite to offend him. And you only said in the question that he is not such a deep friend of yours to (have a right to) be offended by your silence!
Please note that silence may not be a good interpersonal solution in most genuinely interpersonal issues, but silence is a honorable form of hostility here because there is nothing interpersonal about creepy behavior, when men are generally supposed to understand social expectations of decency, and certainly have no excuse for asking sexually loaded nonsense to a woman.
Just give him the deep freeze when you meet him in public as well #. If he directly asks you in person why you stopped speaking with him, tell him that there is no reason. He is not entitled to an explanation because it was he who overstepped the polite limits of an as-yet underdeveloped friendship.
[#Also see my closely related answer to an earlier question on this website, "how to deal with avoiding a person I don't like?"]
As an Indian woman you might get subtle social messages and cultural expectations constantly telling you to be excessively polite and 'not offend' men, but you should remember there is nothing impolite, nor offensive, about your stopping communication with a person that makes you uncomfortable. Especially when his tone and content can be read as sexual harassment. Empowerment starts with stressing your physical and mental boundaries, even through a 'negative' action such as silence. Some Indian girls are even bold enough to scold him for his behavior but you don't need to do that, when silence is easy, polite and even more effective. And please think twice about accepting the friend requests of persons whom you don't really want to befriend, in future.
Note: as pointed out by @Xen2050, you can decide whether to delete this person's telephone number or retain it in a 'blocked' list:
You suggest "Remove his telephone number from your contact list," but saving it in a blacklist or blocked list is probably better, wouldn't want to get a message or call in the future and answer/respond because you didn't remember who it was – Xen2050 [comment]
Good point which I had considered, thanks @Xen2050. I shall include it in my answer but I think it is psychologically better just to erase his number altogether rather than retain it. But OP can choose from the 2 options. – English Student [comment]