What can man [woman] do to me? A lot!

I am sure you have, as I have had, been slandered by someone in your life. The person or persons have oppressed, slandered, hurt, even hated you.

King David’s answer to the question is Nothing! That is if God is for me and stands against those who oppress us.

David reminds us “When I am afraid. O will trust in you. In God whose word I praise, in God I trust: I will not be afraid what can mortal man can do to me ? ” [vv. 3-4]

For Homework: Read about his desperate situation he found himself in
the city of Gath. ]1 Samuel 21-22]
Find the Hope David’s describes in this Psalm and look up similar verses in the New Testament [like Romans 8:31]

When reading James Montgomery Boice’s commentary Psalm 42-106, I found a profound comment related to forgiveness. “The only reason we dare come to God and dare hope for a solution to our sin problem is his mercy” If you have wronged your spouse you need to understand this as you begin to gain reconciliation.
Note : this a big topic and there is more to come…..
For example Brad Hambrick has a two-part series in http://biblicalcounselingcoalition.org entitled The Journey to restore broken Trust part one & two.