DEAR ABBY: My sister, who is quite a bit older than me, was married to a man for more than 20 years. He was a part of my family from the time I was 3. When I was a teenager, he made a “move” on me, which was disgusting because I trusted him. My family swept it under the rug and downplays it to this day. If that wasn’t enough, I twice caught him cheating on my sister. They eventually divorced.

As an adult, I want nothing to do with him. However, my sister and mother insist on him being involved in our important gatherings. I feel they completely disregard my feelings, and I have since removed myself from those gatherings. I feel cheated, but they say it’s “necessary” for him to be around their shared children, and they keep trying to make me feel like I am being unreasonable. Am I? — LITTLE SISTER IN TENNESSEE

DEAR SISTER: You are not unreasonable; you are pragmatic. You come from a family that prefers to ignore misbehavior rather than confront and deal with it. I don’t know if you have had psychotherapy, but from what you have written you might have — and with a very competent therapist.

Enforcing boundaries is not unreasonable. While your sister and mother may prefer hiding their heads in the sand “for the sake of the children,” who by now should be pretty close to adulthood, you have every right to keep your distance. From my perspective, what you are doing is healthy.

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Dear Abby is written by Abigail Van Buren, also known as Jeanne Phillips, and was founded by her mother, Pauline Phillips. Contact Dear Abby at www.DearAbby.com or P.O. Box 69440, Los Angeles, CA 90069.