My daughter in law causing too much emotional & verbal trauma

I am a 58 year old woman from a respectable family Since last 5 years have been verbally & emotionally abused by my dil .Six months ago she gave birth to a baby boy residing with us Her mother fought & insulted me in the hospital .All expenses from hospital to baby needs have been fulfilled by us accruing to a big amount of almost Rs 50 lakhs .The baby did not take mother's milk as my dil was not keen on taking care of the baby for last almost 7 months I have been taking care of the baby .Twice the baby went but had to come back as he stops drinking milk .For last few days she has been verbally abusive in short of hitting me . She wants now to take & keep baby in her room even though the baby refuses to eat & feed milk with her We are being traumatized. We have done our best for the baby ( with ample proof) .She leaves baby goes to her parents , goes for a holiday She is now demanding that she will keep baby in her room even though baby may not eat & loose weight. We ( myself & husband are very attached to the baby Pl advise what do I do