Children custody

Hello Sir/ Madam It has been 9+ years to my marriage. All was going almost well. The past 6-7 months have been really HORRIBLE. I discovered so much which even I didnt imagine in my worst dreams. My husband had drinking habit. I came from a family where smoking -drinking are considered as totally ill habits but after my marriage I adjusted thinking its a culture at my in laws place. With the passage of time my husbands habit of drinking increased. About 2 and a half year ago he left his job saying he cant bear the pressure of private job any more. After this neither he started any Regular work of his own nor he mend his habit of drinking. Life was going on as money was never a problem ( my FIL is still a practicing Advocate & also getting pension as my MIL was a government teacher) Problem started with the time as his drinking habit kept increasing day by day. This year in Jan he hit me on my nose, it bleeded , he felt sorry but distance in the r/ship increased. again life was moving somehow.........from mid feb onwards showed new developments.......he got involved in some other kind of addictions( Afeem etc) , gambling , extra marital affair , threated me many times , abused me, insulted me in front of his friends and one day he told me that his marriage to me was FORCEFUL by his parents........this all has shattered me totally...... I'm a teacher ,have two kids (both boys aged 9 & 6 ), presently staying at my inlaws place and looking forward for a residential schol oppurtunity. But now he is asking me to forgive him for all his acts but now after bearing all this & getting to know that our marriage was not by his wish ....... I CAN'T TRUST him anymore as his extra marital affair is with the lady with whom he was involved in his college time........Everyday he cries in front of him but his tears are just a NATAK...... Now pl guide me if after moving out from my inlaws place ..Shall I apply for DIVORCE ? Will I get my both children custody? What kind of evidences do i have to prove in court if he doesnt agree for a mutual consent divorce? Moreover here I want to mention this also That my FIL whom i mentioned as a practising Advocate is always supportive towards his son.He will never ever Support me if I Step out of his HOME . I'm very stressed and need proper guidance. pl help me