[TOMT] A movie,

where this gentleman gets betrayed by either his wife or lover, who tries to kill him with another man. He then comes back in a disguise, I remember with glasses on, and he kills his wife/lover by pretending to be someone else. He then takes her on a boat, and ties a giant rock onto her, and throws her into the lake to drown.
He then kills the other man by burying him alive. The scene showed the burried guy knocking on the coffin to get out, while this dude sat in a lawn chair; fireworks going off in the background, and he was drinking champaigne or something.