Q. I am the mother of 21- and 19-year-old daughters. They are both in very self-absorbed stages — the older more than the younger.

I have tried to encourage them to think generously and empathetically about others, but my oldest’s self-absorbed attitudes toward myself and family members have been the subject of family concern for eight or nine years now.

I have frequently had to intervene with people who are unhappy with her sarcasm and snarky attitude. My husband sits back and does nothing, even if I talk to him.

I have recently been diagnosed with stage III breast cancer. I’ve told both of my daughters. Despite my diagnosis, I still find myself having to cut through my oldest daughter’s lies and try to help her solve/figure out major issues in her life.

Recently, I opened my computer and found she had left her Facebook page open. I read her messages to her sister, about how “stark raving bonkers’’ I am.

It is a shock and a heartbreak to see how she speaks about me, despite all of my efforts to help her.

How do I deal with this child? How do I deal with my husband, who refuses to get involved?

Heartbroken

A. It is possible that your behavior up until now has actually enabled your daughter to be more of a jerk. Why are you explaining or apologizing to people for her offenses? Is it because you are embarrassed to have raised a daughter who lacks the qualities you prize? If so, you should say, “I’m very embarrassed — but I can’t clean up her messes.’’

I realize that this is disappointing. But — for a variety of reasons, your daughter is an obnoxious and selfish knucklehead. Surely you knew this before you clicked onto her private messages for confirmation?

Concentrate on those things you can control — your health care, your positive relationships, your clean closet. Let the rest go. Not all horrible 21-year-olds grow into horrible adults. Give your daughter the good news: She will now be responsible for her own actions.

Amy Dickinson can be reached at askamy@tribpub.com.