Mariah Carey and Nick Cannon are actually getting along -- way better than when they were together and loathed each other -- but TMZ has learned there is NO chance of a reconciliation. TMZ first reported ... the divorce is a "done deal"and the couple has been separated since May. We're told they are not only on good terms -- primarily for the sake of their kids -- they even went to dinner Friday in Tribeca and shockingly no one even noticed. It's a big improvement from 6 months ago, when there was so much contempt they literally could not be in the same room together. We're told it's all about the kids ... they're both committed to making the divorce as easy as possible on them. But -- let's just say one side tells us -- they will NEVER get back together.

Mariah Carey had a chance to spin her divorce with Nick Cannon, but she said it's simply "too hot" to talk.

Mariah was walking around NYC Monday with her nephew. As the video starts, you can see Mariah putting on a large hat she had just purchased.

But when the photog asked her to comment on her split from Nick, she pled the fifth ... citing the weather. FYI, it was only in the mid 80s in New York Monday.

As TMZ first reported, the Nick and Mariah split is a done deal. It's just a matter of when they make it official.