Dear Carolyn: My daughter is doing very well post-divorce. I can't shake the anger I have for her ex, though. He left the marriage for a co-worker. He never owned up to her being a part of his decision. One month after the divorce was final, out he comes dating her. One year out, engaged. Bought a house with her eight months after that, and in four months they are getting married. It's her third or fourth marriage.

My granddaughters, 4 and 9, are happy Daddy's getting married. Now they'll have a big sister. I just can't act like we are all so happy happy.

I feel that he got a free pass because my daughter has made it all so easy for him, even though that has been hard for her. She does it for the girls. She even has to be around the other woman for the girls' activities as if they are friends, which I know she is not comfortable doing, and watch the other woman with my granddaughters because they have split custody. The idea of her spending time with them while my daughter doesn't makes me sick.

I hate him for what he did to my daughter and our family. I remember the devastated state she was in. She has grown a lot since then, between yoga and counseling. I feel as though I am harboring anger out of loyalty to her, which doesn't do us any good, I know.

Everyone keeps telling me to move on, get over it. None of these people has ever had a daughter go through what I saw her go through. Thoughts?

Carolyn says: None of them has, but your daughter herself has gone through what you saw her go through. By your calculation, shouldn't she be angrier than you are, vs. "very well"?

And not only that, but your granddaughters also have come through this with their optimism intact — so important.

So I wonder. What do you want here? Have you said to yourself, openly, "When X happens, I will no longer be angry"?

I feel near-certain how you will define X: that you just want the ex-husband to apologize or admit he had your daughter's replacement lined up before he left. You want him to pay somehow because you can say, with certainty near to mine, that he (1) hasn't paid and (2) should.

To get out of your dark anger, you have to want out, so I offer these possible motivators:

• Sometimes the way to be "happy happy" is to act like it till it sticks. Exhibit A: your daughter.

• You've outsourced your peace of mind to the ex. When you suspend contentment until someone does something you think you are owed, you let another person — whom you can't control — decide how good you feel. Few happy endings start there. Plus, it gives the person you find most upsetting more power over you than anyone else possesses.

• If he is in fact as bad as you suggest, then I can argue that he didn't wreck your daughter's happy marriage so much as he liberated her from a doomed one.

• You don't know what goes on in any marriage except your own. Maybe the ex isn't guilty of everything you think he's guilty of. Maybe there were irreconcilable differences lurking a few layers down.

• Doesn't your soul deserve better than this? Think about it. You resent that it was "all so easy for him" — yet the alternative is that he suffers. Is that really who you want to be: Person Who Wishes Pain on Another?

• The most persuasive, I hope? You can see the divorce as destroying this little family, or compromising its future, or putting it on an unexpected new path. You have enough information to justify any of these conclusions.

So, why not seize upon the information supporting "unexpected new path" and embrace that conclusion, just for its hopefulness, its humanity, its joy, its deeply practical value in helping people you love?

E-mail Carolyn Hax at tellme@washpost.com.