And she might not truly be mentally ill, just a horrible person who loves to get attention and is now trying to manipulate the daughter into visiting her more often, or doing whatever (coming at Xmas even though it's not her turn) "because she might die/has cancer."

You can't know.

If she's mentally ill, she may believe she might have cancer.

As someone who truly does have a life-threatening illness, I think this is a very cruel thing to tell a child, and she has mental problems. My youngest child is 12, and I do not know how many years I will have with him. My children have to deal with the real thing.

My 95 year old grandmother has been "dying" since she was 45. Some people just like to worry and I would start with that.

Anonymous wrote:
It all depends on the child and how old she is.

I can see myself explaining the details to my 12 year old, who is mature for his age, but I would not say it quite like that to my emotional and anxious 7 year old - more along the lines of: "Your mother is worrying about having a disease, but we're not worried, and neither should you, because it actually appears she doesn't really have it."

Some close family members act crazy occasionally, and the children have enough exposure to them that we've had to explain their foibles.

OP--She is 13, so I think it's okay to explain.

Mostly I think you need to make sure you have her in therapy. Because she won't be able to hear it from you - she will need to realize it herself, and learn to set appropriate boundaries, etc.

It all depends on the child and how old she is.

I can see myself explaining the details to my 12 year old, who is mature for his age, but I would not say it quite like that to my emotional and anxious 7 year old - more along the lines of: "Your mother is worrying about having a disease, but we're not worried, and neither should you, because it actually appears she doesn't really have it."

Some close family members act crazy occasionally, and the children have enough exposure to them that we've had to explain their foibles.

My MIL told us she had cancer. Of course, she didn't, but she did have bipolar depression. Her claims of illnesses like cancer always came at a particular part of her bipolar cycle when she was shifting from the end of her manic cycle into depression. They were a weird kind of paranoia or delusion.

When I look back at that time now, I feel sad, because everyone believed that she was saying these things to be manipulative and so they treated her like she was a horrible person. Her kids, who all by then were mid-30s and up, internalized her "manipulativeness" as a lack if love or care for them. So, sad for her, because misinterpretation of her behaviour prevented her from getting the treatment she needed. Sad for her kids because they grew up thinking she didn't love them enough not to use them, when in fact, when she was healthy, it was clear she loved and was proud of all of them.

Be careful how you handle this. The reverberations last forever. If your DH's ex has a mental illness, it would really help to work with a family psychotherapist for you, DH and bio or stepkids.

My DH's Ex has a habit of making up health issues and now is starting to tell DD about it. We know she is lying, because last year she told the "same" story to my DH and he believed her for a while (at least a month), until she failed to show any proof from a doctor's office when confronted and asked about screening results. She is alive and well of course, living out of state now--thank god. We didn't tell DD about last incident and now she is trying to pull the same trick on my step-daughter by telling her she "thinks" she has cancer. As a step-parent, I think it's the most messed up thing to do to manipulate a child in such horrible way...i.e.. I am afraid I am going to die. I told my step-daughter that her mother did the same thing last year and to not believe her until she shows a test result or a doctor's note. I've told her to not be upset about it and ask her mother for a proof if her mother continues to lie about cancer. We have full custody with brief visitation a few times a year. Was I wrong to tell the kid her mother is a pathological liar and is just trying to manipulate her?