The only way to mininize the harm Lauren can do to others in the future is to share what she has done in the past.
Hence the discussion. It won’t completely stop or change her behavior, but it may lead to her being called out on it immediately when it starts and people cutting their losses sooner rather than later. Or demanding a security deposit and board/training payment up front and no long-term legal entanglements.
At best, she is capricious, immature and vindictive. At worst, she may qualify for an Axis II diagnosis. Either way, she is a liability in one’s business and personal life and at 38 years of age it will be incredibly difficult for her to change her habits of thoughts and behavior even if she wishes to do so.