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Dear Care and Feeding,

My mother and father divorced more than 10 years ago, when I was in eighth grade, after my mother learned my dad was cheating on her. Once my parents split, my father married his affair partner, “Ruth,” and moved out of state. They ended up having two kids, who are now 8 and 5.  After my dad moved out of the house, he never paid a penny in child support and I didn’t hear a word from him again. Until now.

Two weeks ago, my aunt (dad’s sister) called to let me know my father had reached out to her and asked her to ask me if I would be willing to speak with him in person. He had something urgent he needed to discuss with me, she said, but he wouldn’t tell her what. I agreed to meet with him, if for no other reason than the chance to achieve some semblance of closure by telling him off. So he flew into town and I met with him at a coffee shop.

What he wanted to talk about was this: My 5-year-old half-sister, “Amelia,” was undergoing chemotherapy for cancer. While most children with this specific disease respond well to the treatment, he said, Amelia hadn’t been one of them. Her medical team wanted her to undergo a bone marrow transplant—but neither he, his wife, nor my half-brother was a match. He asked if I would be willing to undergo a screening to see if I am.

My planned speech went out the window. I didn’t give him an answer right away, though. I needed time to process this, I told him. But it didn’t take me long to decide to go forward with the testing. I figured that, as a half-sibling, the chances of my being a match were low, and once the test came back saying we weren’t a match, I could tell him with a clear conscience to get out of my life and stay out of it. Except the results came back showing that I am in fact a match with Amelia.

I find myself utterly conflicted. This man who was supposed to be my dad, to love me and provide for me, shattered my family with his selfishness. He abandoned me for the woman he cheated on my mother with. He wasn’t there to teach me to drive or to see me graduate from high school or college. While I spent a decade dealing with the pain and rage his walking out on me caused, he started a new family and forgot I existed. Had his daughter not needed a donor, I doubt I ever would have heard from him again. But here he is crawling to me, hat in hand. Part of me wants to tell him and his wife to leave me alone and never contact me again. I’ve never met my half-sister and I feel no connection to her. But then there’s this stupid part of me that says that my father and Ruth were the ones who hurt me, that Amelia is innocent, and that denying her a potentially life-saving treatment as a means of taking revenge against her parents would be wrong. Please help.

—Point Me in the Right Direction

Dear Point,

Yes, it would be wrong to use this little girl to punish your father and his wife. But I certainly can understand your reluctance to do anything your father asked of you. I don’t think the part of you that’s urging you to donate your bone marrow to Amelia is stupid, though; I think it’s wise and empathetic and is a testament to your goodness despite your father’s coldhearted treatment of you. Let me ask you this: If the child in need of this transplant were unknown to you—if somehow it had been discovered that you were a match for a 5-year-old in desperate need of a bone marrow transplant—would you agree to be her donor? This thought experiment should help you with your decision. I make no judgment if the answer to that question is no. While bone marrow donation is not usually risky—serious complications are rare—it’s true that, like any medical procedure, the process is not entirely risk-free. Transitory side effects are common, as well (in particular, pelvic and hip pain, and bruising). But the equation is lopsided: The benefit to the person to whom one donates their bone marrow is much greater than the drawbacks to donation. Many people do donate to complete strangers.

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I think it’s important for you to separate out, if you possibly can, your feelings about your father from your thoughts about the human being you have a chance to help. If you decide that you want to rise to the occasion of helping this child, I would suggest you let your father know (perhaps relying on your aunt as an intermediary) that your communication will be with his daughter’s medical team, not with him. You still have the opportunity to tell him you don’t want to hear from him ever again—and/or to let him have it with all the rage and pain you’ve been storing up for years. I wouldn’t blame you in the least for doing so.

But I also want to say this: If there is a part of you—another, quieter part—that is hoping to make sense of how he treated you (another set of strands to separate, by the way: the way he treated you, and the way he treated your mother—two different matters), there may be a conversation (or many conversations) with him to be had. Try hard to pay attention to what (if anything) you need from him. Is it an explanation? An apology? A new start? There’s no rush to tell him to never darken your doorstep again—you can do that anytime. Make sure that’s what you want before you do it. But for your sake as well as Amelia’s, decouple this from the decision you have to make right now.

—Michelle

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