If it is RMB50K- don't you have any savings of your own? If you really don't have any $$, can you get cash advance from your credit cards? Don't burden your wife, she is nice already...If she gives everything to your family will your family do the same to her when she needs help?
Let your family know that you are not picking gold here, life is not easy anywhere.
You have to realize who is more important to you-not saying not to take care of your parents however your siblings have to pay their fair shares as well. (you don't want them to turn into a bad habbit to call you for $$$ all the time.)
If I were your wife, I might have to do the same thing to you...She loves you but your family don't give a break...she doesn't see an end...she has no choice but to let you go because she feels you love your family more than her and your kids...
Good luck!