Husband leaves me and son on his Sisters demand

Sir, I and my husband have been married since 2011, after 5 years of commitment b4 wedding, i have supported my in-laws family in social, moral and financial aspects to the best possible way i could. Helped my sister-in-law to get married in 2012 to a suitable person, who are way better financially from what we are. For this wedding i have provided monetary support also, but without my knowledge my mother-in-law and husband had made about 20 lakh loan for the wedding to be done in a good manner. now my husband, MIL, SIL and her husband together are pestering me badly for taking about 20 lakh loan and clear off their debts. I have a 2.5 year old son to raise and meeting my daily requirements is a challenge for me with my income and i am not in a position to take this loan, because of this my MIL, SIL and her husband are provoking my husband to separate from me when i am not contributing to their loans. LAst year also my husband left me and my 1.5 year old son for about 2 months and stayed at his parents home. with elders couselling we lead a near to normal life for an year and this year about the same timing he has left the home again and neither he nor his family members are responding to our phone calls or any mode of communication. Meanwhile i have learnt that he had filed for Judicial Separtion last year itself and then came back to stay with me. This is really causing a lot of mental trauma to me, kindly suggest what best can i do to save my marriage atleast for my son's sake.