Go to the newsfeed and find a recent post by her. You will see "shows in newsfeed" with a check mark. Click it. You'll no longer get her in the feed. Or go to her page and click on the button that says friends you'll see the same "shows in newsfeed" uncheck it.
I would recommend you unfriend her. Man I did this a few weeks ago and while the temptation to look at her page is still there I know I wont see everything she posts now and the temptation isn't as great, I find my FB time isn't focused on her and looking at her page but friends and family. Unfriend her!
Me 32 W 30 Married 11 D10, S6 BD#1 January of 09 OM#1 2005 OM#2 Dec 08 OM#3 March/April of 09 Back together August 09 OM#4 May 13 W moves out June 2013 BD#2 June 21 2013 Filed July 2013 D final in Oct