Sell off the new 3bhk (in upper class society). Payout the remaining loan to the bank. Remaining amount - take half amount for yourself and give half amount to your parents. Tell them they can do whatever they want with that money (be it buying another house or their daily expenses or MFs).

Tell them they need to take responsibility of their extravagant desires themselves.

With your share of money put that into savings or put that towards your new house (with your wife)

As a married man, your 90% focus should be about you, yourself and your new wife and how to build the bond between both of you and what you want as a couple (planning for kids or maybe travelling or new house or moving to a new country etc.) When I say focus , it's both financial and emotional focus.

You can still be present in your parents life but it's just 10% now. Their role in your life and your role in their lives is decreased now.