Having trouble letting go of ex-sister-in-law

I ended a 5 year marriage with an abusive husband, I should have left many years before, but in my culture, you just can't leave a marriage like that and who was I kidding, I was so young and afraid of ruining my family's good name. All I can say is that my ex husband put himself first above all others, even 2 innocent babies that would never be born. Broken hearted and alone, I decided to leave after the 2nd miscarriage, I just couldn't do it anymore. I didn't have family in town and in the 5 years that I had been married I never made any "real" friends other than my sister in law. When I left her brother, I don't know what happened. We were so close, I was there for her through so many things and was always her rock, I was the one that she cried to when she had breakups with boyfriends, girlfriends who betrayed her, parents who were going through divorce. I guess I expected her to love me enough to understand why I was leaving her brother and understand that I wasn't leaving her. I guess what they say is true, blood is thicker than water. At first, she used to call and ask how I was doing... then I started hearing things back that I had only told her. I found out she was just calling to find any possible dirt on me and telling her mom so they could pain me in a bad light. To this day my ex husband's entire family maintain that I left him to be with another man. I shouldn't care so much about what they say or why they don't care about me anymore, but I do. I find myself addicted to reading my sister in law's blog even though it kills me each time. She writes about how she can't rely on so called friends, how only "real" family matters to her. She writes to her other sister in law calling her "my best sister in law ever". It hurts me so much to read these things... yet I find myself addicted to it... and after I torture myself with reading these thoughts of her, I can't help but wonder why she doesn't care about me anymore, why does she want to hurt me? She herself saw what her brother did to me all those years... she herself hated him for it. Now she hates me because I had the strength to leave him. Is it really my fault that he now lives a life filled with drugs, alcohol and partying? I tried to save him from that, I tried my hardest with all my heart and hope for 5 years, and after he took away 2 precious lives from me, I couldn't do it anymore... I guess what hurts me the most is not my experience with him... but with my sister in law. How can I let go? How can I get some closure so I can move on with life and make new friends?