Should I un-friend and block my sister-in-law in Facebook?

I accepted my sister-in-law's invitation to be her friend in Facebook late last year. A couple of months ago we had a clash when I got sensitive over her and my brother Caroline instead of Carrie, my nickname. It was an outburst on my part and she took it in a negative way. Right after the incident, she wrote on her Facebook wall which I read, of course. Without mentioning my name and for everyone to read. She wrote, "Just wish people would stop pretending to be good when they're not...it's better to show off your real person than trying to be goody nice. You're far from being blesseD! good riddance." We haven't talked since that happened. I have a bad feeling about her and knowing we are connected on Facebook is making me uneasy. She can't see any of my postings and just minimal photos. But still....Should I un-friend her and block her so she won't know if I left Facebook or something?