As I was reading Ed Welch's Running Scared (which I have not finished, but highly recommend, nonetheless), I ran across something helpful in dealing with this very question. He's writing about the fear of death and judgment and I thought it worth passing along to you.
When you belong to the King, how can you discern the difference between the Devil's condemnation and the Spirit's conviction? How can you determine if you are in the bogus courtroom or the real one?
In the real courtroom:
you know your good deeds are not enough
your hope is in Christ alone for your deliverance
when convicted of sins, you are pointed past your sins and on to Christ
the last word is always hope.
In the Devil's counterfeit:
the attention is all on your sins
you stand and fall on your own behavior
you are alone without an advocate
questions are raised about the extent of God's forgiveness.
(Welch, p. 220-221 or location 2410-2416 in kindle.)
When Satan tempts me to despair
And tells me of the guilt within,
Upward I look and see Him there
Who made an end of all my sin.
Because the sinless Savior died
My sinful soul is counted free.
For God the just is satisfied
To look on Him and pardon me.