Diddy just took the on-ramp to the high road ... showing nothing but pure class and congratulating his ex, Cassie, and her BF on their pregnancy news.
The rapper gave the couple a huge shout-out on Instagram and made it crystal clear ... there's ZERO hard feelings. In fact, he wishes Cassie and her man, Alex Fine, nothing but the best. Well, love to be exact.
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What makes the news HUGE, of course, is Cassie got knocked up less than a year after splitting from Diddy, who had been with Cassie for about a decade.
Remember ... Diddy hired Alex -- a pro bull rider and personal trainer -- to train Cassie. Sources told us Diddy felt betrayed at the time, because he felt they hooked up BEFORE the breakup. Our sources connected to Alex and Cassie insist they weren't together until Diddy was outta the picture.
Whatever the case ... bygones are definitely bygones by now.