We've got an explosive exclusive!  The YBF has just learned that not only are Usher and his new boo Grace Miguel ENGAGED....but he knocked her up as well!

"Oh snap!" doesn't even suffice in this case.  We've got all the exclusive juicy details when you read on...

While Usher and Tameka Foster officially divorced in November, they were still legally married (and together) when Usher started dating former Def Jam exec Grace Miguel.  And Usher is clearly continuing his pattern of quickly marrying an older woman and getting her impregnated sooner than he can say "Daddy's Home."

This past Sunday, Usher was caught in Atlanta's Piedmont Park with his two sons, Naviyd and "Cinco", and Grace.  When the two were asked to pose for a picture, they both turned and moved very quickly from the cameras.  Still, the pic (above) was snapped from behind (Grace on the far left, Usher and the kids on the right).

We're told that Grace, who is still surprisingly legally married herself, is about 3 months along and not showing much yet.  But she will be soon, in case Usher predictably tries to deny our story.  It's well known throughout Usher's circle that Grace is expecting, but folks for some reason are not speaking about it.

So what did Tameka think about Usher bringing his kids in public with the woman he essentially cheated on her with?  Well here's what she said on Twitter last night after she found out Usher let Grace around the kids:

Damn Ursh: Two sons and a divorce under your belt...with another wife and baby on the way?  This ish is about to get ugly.  You heard it here FIRST!

Photo via The Socials