I'm sorry you're dealing with insecurity and what you call obsessiveness. I can relate, actually. My ideas: 1.) Be kinder to yourself. This behavior and thought pattern had to have come from somewhere and it was probably a painful place. Beating yourself up over feeling pain probably isn't the most helpful thing. 2.) Maybe find a hobby. Do something you really enjoy and are interested in. Maybe then you will be busy with that instead of checking up on people on facebook, etc. 3.) Consider therapy.

You'll get through this. It may not feel like it now. But personal growth takes time, and sometimes life really hurts. Go easy on yourself.

Edit: I just read your follow up post. I have a 4th idea for you too. Are you social? Or more isolated? What about connecting more with people and engaging more in your community? That is, if you don't already.

What happens when you try not to check on them? What if you just "sat" with those feelings of worry.