Based on what youre saying, I kinda get why you're reluctant and a part of me wants to say kudos for staying your ground and Mrs shouldnt be listening to her friends, these things will only ever make things worse.

But none of us here really know you or your wife to give a piece of fair advice. But being married to your wife, Im sure to some degree you understand your wife and the things that influence her. So give it time and then talk to her about it, hopefully one that doesn't end with an argument.

If that calm reasonable heart to heart talk does not bring a favorable conclusion then, by the obvious, you would have to decide if some money is worth more than your relationship/family.

Also, I could only assume you child is still a baby given the milk and diapers, so maybe you still go easy on saving up for his education. Being prudent for the future is great and all but sometimes "right now" is more important.
add: :< 5k allowance on top of her bring home of 5k , when she does not contribute to the household maintenance is too much. Im sorry I dont think youre the one to compromise on this.

hhahaha be careful with this, especially

if the apartments is under your name..if one day she boikot about doing it, you will have trouble find tenant..
if the apartments is under her name..if one day things dont work out say bye bye to your assets