WATCH: Mary Trump Goes Scorched Earth on Eric Trump

Mary Trump recently posted a video where she responded to her cousin Eric's attacks on her brother, Fred III. 

Fred Trump III has now joined his sister Mary in discussing what it was like growing up in the Trump family. Fred recently wrote a book where he reveals a story where Donald Trump told him to just let his disabled son die. 

Eric Trump treated Fred's book as a betrayal and went out of his way to rip his cousin, writing in part, "to read this garbage and see that he has now followed his troubled sister [Mary Trump] to simply earn a quick buck is disgusting, disheartening and a prime example of ‘no good deed goes unpunished.’"

Mary Trump responded, beginning by stating that Eric is, "beneath my contempt. [I couldn't] allow this statement to go unchallenged, not only because it is full of lies and misinformation, but because he’s using his vast platform to punch down."

The message from Trump continued:

"If he had any sense of basic human decency, he would understand the bargain he's made and at the very least, not attempt to pass off a blatant theft — from which he's benefitted — as an act of charity. But he's had very good teachers, and instead goes for the threat and the lie while rejecting truth and compassion, because like his father, he's weak and he's cruel in the way of small, unaccomplished men."