Slim Jxmmi dropped some disheartening Twitter bombs on fans of the "Black Beatles" rappers Saturday morning, including 3 he later deleted implying he's parting ways with his brother, Swae Lee.

One said, "Y'all won it's a wrap," while another was even more telling, with Slim saying ... "I'm not Rae Sremmurd I'm slim jxmmi and ima sink or swim by myself."

Jxm also boasted he'd bought his mom a home off the money he made from his own work ... which is a tweet he actually left up.

The 2 have both done recent solo work but confirmed they have a new album coming out in early 2019 ... called "SremmLife4."

This isn't the first time there have been rumors of a breakup, but they've denied them in the past and maintained all was well between the siblings. It seems like it could be different this time.

Interesting note -- the last time we heard from the rappers was last week when they were in New Zealand, but only Jxmmi was seen ... getting involved in a bloody street brawl.