how to stop thinking?

I just cant stop thinking of my MIL who lives in another country but she interferes in my life one way or the other. I just so damn hate that woman. She is a wicked woman with wicked thoughts. I am unable to focus on my life. I think of her all the time on what kind of a mean woman she is. Her son-in-law stopped talking to her because she tried to act mean to him as well. Since I love my husband Ican't just shut myself from her. help! advise?