Just three months after giving birth to their baby son, Ciara reportedly called off her engagement to fiancé Future because he cheated on her with Rihanna.

According to MediaTakeOut.com, the Atlanta emcee and the Barbadian singer, who previously collaborated on "Love Song," worked together all summer on several tracks for RiRi's upcoming new album. The duo spent many late nights in the studio together, while the "Body Party" singer was at home with the baby.

"Future promised that he would just make music and then come back home to be with Ciara and their baby," a source close to Ciara revealed. "But he was out in the club with [Rihanna]."

Also, CiCi strongly disliked the "Diamonds" singer even before and when she suspected that Future was having something more than just a business relationship with her, she had no choice but to dump him.

"Future is a rapper, so he's going to be messing around. It's one thing if he's with some stripper on the road, or with one of your baby's mothers. I'm not saying it's right, but things happen," the insider added. "But to be [allegedly] f*cking the nasty b*tch that your fiancé hates... while Ciara's at home taking care of your baby less than a mile away. That's some sh*t you just can't forgive."

Meanwhile, Ciara apparently feels like "one of the stupidest women in the world. All of her friends told her he was no good from the jump. They all told her not to trust him, but she was in love and she ignored all her friends who warned her about him," a friend of Ciara's told HollywoodLife. "That's love for you though. It makes us all do crazy things -- things that we all know damn well we shouldn't be doing."