remote spying possible? HELP!

I recently split up from my husband and last week I found a hidden listening device in my house. Feeling suspicious I have been keeping an eye on my mac. Yesterday, I was searching for signs of spying and I am not sure how but I came across many files of things I have been doing (records of events) going back to 2010 and emails between my husband and his friends saying not very nice things about me. My camera then took two pictures - one was taken and I was not even touching the laptop! I unchecked all my sharing options as I panicked that someone was watching me. Since then I have not been able to find a trace of what I saw. It is definitely possible that he has been able to set up remote access before or after we split. Would he be able to listen to my conversations and watch me through the camera? Is it possible for me to see his computer from mine if he has remote access?

I have downloaded a demo of MacScan and run it and so far nothing. I have also unchecked all sharing boxes, turned on my firewall and changed my login password. Is this enough? Should I reinstall the OS?

Any advice would be very much appreciated......