K.F.
A funeral isn't a forum for the dead to speak but a forum for those still living to reflect and remember the deceased. The beautiful thing about a funeral is that the dead person can want what they want but the living have the final say.
NO, these words of hatred and poison should NEVER be shared. SIL's father may be set in his ways and may never change but that shouldn't mean this poison of bitterness and unforgiveness should continue beyond his life.