Hi, thanks for using JustAnswer.com I am Cris. Sorry to hear about your issue.
What you can do is go in and change the password ***** any security questions on your facebook. If you feel this person may have access to your email you should also do the same change password ***** security question. They will not be able to reset your facebook password ***** email access or access to the mobile phone on your account.
I hope this helps or answers your question. If you have any further question please let me know I will be glad to answer them. Please take the time to rate my service and submit at the top.