Section 125 maintenance and support claim by mother unjustified

We got married in Feb 2006 and out of marriage a boy child was born in 2006. Then due to financial incompatibility we sought divorce under mutual consent in 2015 and the same was granted by the honorable court in July 2016. The child’s mother refused to hand over the custody of the child to me citing me incompetent to financially raise the child. Also, for compensation and child’s maintenance I had to hand over the Fully Furnished Apartment 2 BHK - 750 sqft area whose current value is Rs 60 lacs which was jointly held by both of us through a Gift Deed during the divorce proceedings. During the divorce proceedings the Mother under oath said in front of the honorable judge that she wants to keep the custody of the child and would not claim any maintenance and support as I am incompetent. On March 2018 , I got remarried and out of marriage a girl child was born in year 2019 and the same year My ex-wife out of vindication filed a case against me, claiming Rs 50000/- monthly as the maintenance and support for the son, on September 2019 under crpc section 125. Whereas the mother is a business woman with sound financial background earning a modest 2 lacs per month and holding a residential apartment along with her mother in a posh locality and also heir to multiple ancestral properties amounting to Rs 25 crores. On the order of the court, on 17th March 2022, we submitted the documents and evidence of all our income and expenditure. The detailed breakdown of my expenses and liabilities as a sole earning member in the family with dependent 4 senior citizens, my wife and my girl child. With evidence and supporting documents to prove the fact that a nominal of Rs 3000 – Rs 5000 average monthly balance remains after all expenditure. On 21st May the court gives verdict that we have to pay Rs 17000/- seventeen thousand rupees monthly starting from September 2019 with arrears coming to Rs 6 Lacs approximately. I submitted all original copies of 6 months bank statements and IT return for last 3 years. Where I mentioned it would be impossible for me to pay more than Rs 5000 per month to support my child. For the past 10 years I am bearing the expenses of my parents and my physically handicapped bed ridden Uncle in Kolkata. My father is not a pensioner. They don't even have a mediclaim policy. My humble request for help to come out of this situation. 1) How I am liable to pay arrears of Rs 6 lacs as maintenance when I don’t have that money as liquid assets? 2) Would I be liable to pay that amount by selling off my residential apartment and deprive my elderly parents, dependant family and my 2 and 1/2 year old daughter. 3) What is the justification behind setting a flat rate of Rs 17000/ for a child’s maintenance in Kolkata from 2019 onwards? 4) Is there any hope to challenge this order and find a legal recourse? 5) Can I claim custody of my Son instead of paying maintenance of exorbitant amount which has no justification?