I need a seperation from my husband

Hello sir i have been married for 20 years and have two kids aged 17 year old daughter and a 14 year old son. 2 years after my marriage i had caught my husband cheating on me . After a long struggle, adjustments and need to fight for my marriage for five years everything seemed to settle down and get better ,however 5 years ago i caught them red handed in my empty apartment having sex. after which i was shattered and went to my parents house in the usa .as usual he managed to convince me with false promises and emotional blackmails that i have to forgive and move on with him.my in laws have always supported him and told me to adjust because of the kids,and i always did .however nothing has changed .in fact he has more and more harassed me mentally by throwing his affair on my face and on the other hand he has always tried to show me as a characterless woman and suspects me with everyone on the face of this earth .i have changed over the years so much that i let him live the way he wants to without questioning him however he does not let me live my life peacefully with my kids ,abuses me in a very dirty language ,stops giving me money since i stopped going with him to our business , and also forces me to get physical with him. i no longer want to live with him as i feel scared for my life and on the other hand cannot live without my kids and cannot take care of them financially. he always pressurizes me into coming back or patching up by trying to prove that he loves me so cant leave me ,i believe that he suffers from a split personality disorder I'm mentally drained in this marriage please advise what i can do in this situation thanks