Britney Spears' son, Jayden Federline, went on a rant, calling his grandpa, Jamie Spears, horrible names and also saying his mom may never sing again. Jayden went on Instagram Live Tuesday and made it pretty clear ... he's spending way more time with his dad, Kevin Federline, than Britney. He said at one point, "I'm gonna visit her in like a couple weeks cause I'm with my dad right now. I'm doing pretty good."