I have had two breakdowns -- one after the end of my marriage, and a second one of the career/identity variety. Based on my experience from the first, I handled the second one differently. I fought the first one. Hard.
No matter how curious you are about what your ex is up to, there's never any good that can come out of scrolling through his/her Facebook page. Let go of this bad habit and let go of the ex so that you can move on to better things.
If you deny the possibility that someone could be hurtful, you put yourself and your loved ones at great risk. Facing this truth, on the other hand, is empowering and will enable you to make the kinds of choices which will give you a better life.