Yes. You can hide them. What you need to do is make a friend list just for them. I'm assuming you know how to do this, you can create lists for friends, work, school, etc. Once you put them in their own list, go to chat and click on friend list. From there you can customize what friend list you see on facebook chat. I'm pretty sure that this also makes you invisible to them.
If you really want to hide from this person though, you could always just unfriend them.
