"Deal with it!"
Translation:Πάρε το απόφαση!
I would say that the Greek translation might refer to something a bit more personal, without excluding everything else. There are a lot of expressions that are used in contexts like these, like "Χώνεψέ το" (technically, "Digest it"), "Ό,τι έγινε, έγινε" ( "Whatever's done, it's done) etc. I'd say the second one is more commonly used for things we have no control over.
Good thinking, but no. :) Αντιμετωπίζω suggests you are going to take (some) action, it's closer to 'face it' (αντί + μέτωπο + -ίζω), while the sentence is meant as 'this is how it's going to be, make your peace with it / come to terms with it'. For example, the expression αντιμετωπίζω ψυχολογικά προβλήματα means to face psychological problems, with to face pointing to the resulting difficulties you have to overcome / work against rather than the suffering (for which you can say 'υποφέρω'). In short, Αντιμετώπισέ το would be a call to action.
As a native English speaker, the expression "Deal with it!" is a recent modern slang phrase, and, at best, is an abrupt thing to say! It's often used by overbearing people and bullies as an instruction, to put another individual down in their place in short order, and it's rude!
It's not something I would wish to say to anyone in conversation! Is this the expression which Duolingo is trying to translate?