They repay me evil for good and leave my soul forlorn.

Forlorn is a great word here.  When a friend misjudges your actions, and spreads it around as truth, or when you do something kind, and the person throws it  back in your face – forlorn definitely describes the condition of your heart.

vs. 27  The Lord be exalted who delights in the well-being of his servant.  But,  we know the One who delights in our well-being.

vs. 22  O Lord, you have seen this; be not silent.  We know the One Who sees it all.

vs. 10  Who is like you, O Lord:  You rescue the poor from those too strong for them. We know, and are loved by, the Great Rescuer of our souls.  He an be trusted to make a forlorn heart fill with joy again.