So far, all that is officially publicly known about Mimi’s death is that it was unexpected. As in, she had no underlying health issues that she or anyone close to her spoke out about leading up to her death. There are some comments on her Instagram where her followers claim her family revealed on Facebook that Mimi was in a car accident. 

However, because it hasn't been officially announced just yet, those are mostly rumors. It would make sense, since a car accident would be an unexpected event to lead to her death. No matter what it was, though, it’s obvious that Mimi is dearly missed by family, friends, former colleagues, and fans.