Can I keep my sister in-law away?

-my husband and I no longer want anything to do with his sister. Every time she came back in to town she hascaused nothing but trouble. Now she has moved back in totown and is living with her mom and stull continues to cause trouble. She is bad news and is trying to brake up our marriage. Our lives are so much better with out her in. She said that my husband can bring the kids around but that I not allowed to come around. She is not trust worthy and we wont allow our kids to be left alone with her. What can I do to keep her away. She is not good for our kids to be around.a restraining order, just say she threatened you