The reality TV star publicly blasted the 'R.I.P' hitmaker on Twitter after their relationship ended last year, claiming she slept with up to 20 men while they were together but Rob, 25, says he blasted her in order to stop himself from taking her back.
Speaking on 'Kourtney & Kim Take Miami', he said: ''I posted what I posted to keep myself from taking her back. Every time she messed up, I took her back for over a year now. I just had to do that to make her hate me.''
Rob's sister Khloe, 28, said the relationship took its toll on Rob because Rita didn't want anyone to know about them.
She explained: ''Rob got out of a really weird relationship. They were actually together for about a year but Rob was never allowed to admit that they were actually an item. Because she's in the entertainment industry, she wanted to present herself to the world as a single girl.
''I think Rob got really depressed through this relationship.''
His other sister, Kourtney, added: ''She's the one who's in the wrong but she'll probably try to make it like you're in the wrong for posting it. Instead of dealing with it privately, it's just becoming a public matter now.''