It's a difficult one because although you have split up, you are still interested in them and want to know what they are doing. It's like there is still a connection there. I had the same thing a few years ago when I split up from my husband. I could see what he was doing etc every time I went into Facebook. Eventually after a month or so I deleted him as a friend on FB. It's difficult, but in order to move on you have to unfollow your ex. Remember why you broke up, and you should then see why it's time to go forward with your own life.