The ending to Genesis give us a glimpse of the emotions that were felt by Joseph's brothers during the duration of their time in Egypt. After the death of Jacob, the brothers were crippled with fear that Joseph would finally have his retribution for their decision to sell him into slavery so many years back. What's s0 sad is that they had complete freedom, but they lived in fear. Joseph had forgiven their debt, but they continued questioning whether or not the forgiveness was real.
There are Christians like this, too. They have been forgiven of their debt of sin, but they constantly live in the fear that somehow this is too good to be true. Joseph's response must be a reflection of Christ's response: he wept at their lack of acceptance of the gift of grace. Have you accepted the forgiveness of Christ? If so, then live free in the knowledge that your debt has been paid in full.