How can I believe that God is in control when something bad happens?
It is hard, and we don't make light of it. We don't blow it off or act chipper. We hug. We weep with those who weep. And we embrace.
But when the question arises—and it will arise, sometime sooner or later—as to where was God in all of this, I think two things are essential:
1) Go to the cross of Christ and realize that God designed this horrible horrible event for our good.
If God can be in control of the cross with all of its sin and all of its horror and pain, then he can be in control of our pain and horror.
2) If we try to rescue God from his sovereignty and take away from him his involvement in the pain that just came in to our lives, we also lose God's present power to turn the pain for good. The price of denying God his sovereignty over pain is too high to pay, and people can see that.
I just want to encourage people that, even though things are sometimes hard, God is mysteriously loving and sovereign in all that comes our way. To lose him as sovereign and loving in that moment is to lose your hope for the future.