From what I've read from your other posts it seems you've been making a serious effort to get back together with her. She might just view telling her about your heart attack as another attempt to drag her back into your romantic world, which is something she seems to want to avoid at all costs. Or maybe she's just trying to send you a message she doesn't think you have gotten yet.
I think butterfly just means there are many other girls out there, even if right now you can only see one.
Hope your recovery goes well.