Future went off on Ciara yesterday, calling his ex an a "bitch" and arguing he should be able to see more of his son Baby Future since he's paying her 15K a month in support.

Now we're getting more info on what was behind his Twitter tantrum. According to sources who spoke to TMZ, Future had planned a big Christmas dinner and wanted all of his children in attendance.

He thought that Ciara had agreed to sending Baby Future, but she never did, sending Future "through the roof."

The source also revealed that Ciara and Future haven't spoken in a year, and communicate through a family member. They said that Future was hoping Ciara's new relationship with Russell Wilson would help to thaw things with him. But so far it hasn't worked that way. (Future's comments about Wilson probably haven't helped here.)

As for Ciara ...

Her people told E! News that she's "never prevented Future from seeing his son and that Future does not and has not paid $15,000 in child support."