So Shabba,
What are you doing to reduce infamy? The only things I've found so far are
1) A Ruler with High Diplomacy - (Kinda hit and miss unless your Government type allows elections)(-10% of Diplomacy skill per year, so -0.1 to -0.9 range)
2) An advisor with +Diplomacy (Ambassador, -0.05 to -0.45 range)
3) Cultural Decision - Support the Florentine School (only -0.1 Inf a year but meh)
4) Release Vassals - (-2 Inf per province!)
And then wait.
A lot