Dear Prudence,
My sister Barbara is obsessed with my ex-boyfriend, Tom. I knew she had a crush on him when we were dating—she was 15 and we were in our 20s—but that was over a decade ago. I figured that she would have gotten over him, but apparently the exact opposite has happened.
I found this out last week when she turned up at my house with a knife and threatened me to make sure I understood I’d “had my chance” with him and it was her turn. She didn’t hurt me, but she did break a few glasses when I tried to point out that Tom was gay (I’m a guy).
In the end, I just said what she wanted to hear (I don’t know if that was a mistake or not) and called my parents once she left.
It turns out that my little sister, who lives a perfectly functional life, spends all her free time obsessed with Tom. She follows him on social media, she has ledgers of all the secret messages he’s “sent” her, and has made a few troll accounts to bad mouth and attack his boyfriends. She’s convinced that he’s going to marry her as soon as it’s the right time. Also, when she was 17, she flew to where Tom was living and turned up at his door to try and seduce him (no one told me about that at the time).
My parents insist that until recently they thought it was harmless, just like a boy band crush. It isn’t, my mom said, as if it affected her life. Apparently, what changed is that Tom is moving back home for a while to take care of his father who has cancer. To Barbara that meant it was the “right time.”
I think we need to tell Tom what’s going on and seek medical help for my sister. My parents vacillate between agreeing with me, saying that Barbara knows it is a fantasy, and weirdly being part of it by suggesting that maybe Tom and Barbara could get together after all. I’m so bewildered by all of this. Not only is my sister clearly unwell, but my parents seem to be embroiled in it somehow. I’ve maybe not been as close to them as I could have been, but I genuinely never suspected anything like this was going on. I’m floored. I don’t know what to do next. Or how to start doing it.
— A Bit Scared