I was by no means suggesting you were going to sue...I was just noting that there really isn't anything we can do to prepare for this situation. It comes up with all fields of work, people branch off, start their own companies and often bring clients with them. If you plan to do outings and park playdates with this person then I do not think laying her off is going to go over well. Even with the best intentions, laying her off will create tension. Obviously you need to decide if you can continue to work with her. But if you plan to stay on good terms and hang out in the future then I don't see much to do other than continue on. You can bring the topic up to clear the air a but be prepared to handle that conversation if you don't like her answer (she approached the family etc).