Abetment of suicide

Hi, I am Bhupen. My sister was married for 10 years to a very violent, abusive and chronic alcoholic person. He beat her up regularly, and even his mother, sisters and her brothers in law tortured my sister no ends. After one such incident, I brought my sister home, but could not get her two kids with her. After a few days, my sisters' in laws and husband started approaching us for a reconciliation and requesting us to send my sister back to her inlaws. After around 20 days of persuasion and the fact that my sisters didnt have her kids with her, based on the assurances from her in-laws, she left in the night of 22/11/16. Then we got to know in the afternoon of 23rd that she had attempted suicide by consuming anti-depressent tablets. We took her to hospital and somehow have been able to save her after she stayed in ICU for three days. Now she is staying at my home. We have given a complaint of this incident to the police on 27/11/16, after the police officer did not turn up at the hospital to take my sister's testimony. I discussed the case with IO at the PS who now is saying that it is not possible to lodge an FIR under IPC 306 in this case and is insisting on sending the case to Women Cell. Please guide me with regard to this situation as to (1) whether the attempted suicide has to be successful, before an FIR can be lodged? (2) What action can be taken against my sister's husband and her in-laws for the cruelty caused and the compelling circumstances which drove her to attempt this suicide? (3) Whether my sister can be charged under IPC 309 for this attempt despite that fact that there were compelling reasons for her to do so? (4) Any advice on how to handle this case and how to proceed? Thanks a ton.