"It's all over between us" would seem to get the point across better than "everything is over between us". I'm not even sure if the latter is acceptable in English.
"Everything is over between us" is fine in English, but "It's all over between us" should definitely also be accepted.
Why not "is ending"? Why "is over", which I take to mean"has ended"?
Everybody seems to read the verb as past (נִגְמַר), not present (נִגְמָר). So both would be correct, if both make sense.
Everything is over, and Everything is finished mean quite different things. The former means our relationship is terminated; the latter means we have each discharged our obligations, such as in a contractual relationship.
כְּשֶׁמִּישֶׁהוּ אוֹמֵר מִשְׁפָּטים כָּזֶה, לֹא הַכֹּל עוֹד נִגְמַר. כַּאֲשֶׁר בֶּאֱמֶת הַכֹּל נִגְמַר אֲנַחְנוּ לֹא אוֹמְרִים כְּלוּם. אָז זֶה המִשְׁפָּט שלֹא נָכוֹן...