Documentation is your friend.
In a scenario like this, the best thing you can do is clarify any potential point of uncertainty between you and this developer in writing ( email ). You won't have to do this for long obviously, but if you feel as though they may come after you in some subtle way, it is only prudent to attempt to protect your selfyourself.
Also, be sure to keep your manager in the loop on any interactions that have the potential to become a land minelandmine. This way you can attempt to avoid having any additional departments becoming involved ( HR comes to mind here ).
I know this will be a bit of a documentation pain for youin the neck, but it is the best way to protect yourself.