New Member. Hope you can help me

Guys, need help....
Me and my wife got separated last 4 years.We have a daughter,last year she was with me and I provide her basic needs and half of the tuition fee and the service, my ex wife provide half of the tuition fee,the school supplies and the food allowances(not money).Thats fine with me. But this year I had a new son with my new girlfriend so I decided to gave my daughter to my ex-wife.Now she wants me to sign her self made agreement to give the 1/4 of my salary every cutoff for the needs of our daughter, giving what my daughter needs is fine with me but is that right to give the almost 1/2 of my salary considering I have my new child to support too and personal expences?What if I cant give the right ammount she wants because I have emergency expences?Honestly I have my debts now cause my girlfriend had a C-section with our son. Me and my exwife always fight to each other because I gave my daughther food allowance and money but she thinks it is not enough but truely it was all I got.Can I refuse to sign her self made agreement? She also had a good job and source of income.In the first place it was her fault in our seperation because she had an affair with her co-worker,All just I want is she must also consider that I have also my personal expences and new child, and I will not forget my obligation with my daughter.Please help. Im very very stressed right now cause she always bangging me with text messages.TIA

First of all, your situation's a bit messy, so if you haven't found the answer I suggest na ilapit mo na sa isang attorney which specializes in family law, nothing beats a legit advice especially if it's for your peace of mind. NCR is full of good lawyers, if taga dito ka lang, I know one that might help your case or at least mabigyan ka ng matinong advice.Here's the link of their law office https://alburovillanueva.wordpress.com/contact-us/