My Brother-In-Law has been in trouble for messing with children...?

My BIL is menatlly handicapped, 48 years old and has been arrested and several times been accused of messing with little children. He has gotten off, because of his mental handicap... Anyway, here's a brief family history on this issue. my MIL was molested until she was 14 by her father, but yet, she thinks her father is/was the greatest man that ever walked the earth. He eventually committed suicide. My BIL (in question) is the same way. The whole family makes excuses for him and my husband keeps telling me that he thinks his brother should be able to come visit to our home with his mother. He keeps saying that nothing will happen as long as we watch him and the kids. I'm sorry, but the thought of this man coming around my kids, or any kids makes me totally sick. The BIL says that he loves our kids, wants to see them... My MIL thinks I'm awful for feeling the way I do. My husband keeps saying, "He's got the mind of a child." I really need some input on this.