hi greengrape,
My thoughts were :
2 things u did wrongly. Firstly, why in the first place did u allow yr parents know about your pay? Secondly, why allow them to demand? Sorry to say that... but for the sake of self interest, i never give out my actual pay amount, even to my parents. Though they dont demand and I can give any amount i deem fit for them. Of course, my new year ang bao and birthdays gift are of substantial value to the best of my ability lah.
In your situation, if your parents are so demanding and asked for 25% of your paycheck, I guess u can't be a SAHM.
But if no choice, I guess u have to work out your sums, give them an amount u think is at your best effort. Bear in mind now that u have your own family, interest of the your family comes before anything else. While you are doing this, I guess you cannot splurge on branded stuff, no long vacation for the next couple of years and you just have to be more discreet in your spending.
At the end of the day, if you cannot afford to give in to their demands, you hav to thrash it out and work out a balance. Well, they cant put a knife to your throat and ask u for money right.. At max, during negotation, the relationship will go a little sour, but it will cool off... when they want to see their grandchild..
Think of the worst case scenario that will happen, eg, if you tell them that 200 is the max u can afford now. Pre-empt their reaction, be prepared to know how to deal with such reactions. Stand firm, have your own reasons at your fingertips. You wont lose out..
Good luck.