Revelation 19:2

For true and righteous are his judgments
As in (See Gill on Revelation 15:3), (See Gill on Revelation 16:7): this is to be understood of God's judgments in general, and is a reason of the attribution of praise and glory to him; which may be said to be true, because, being threatened, are now fulfilled; and to be "righteous", because according to the demerit of sin; and particularly God's judgments on antichrist are intended:

for he hath judged the great whore;
Jezebel, Babylon, the Romish antichrist, before spoken of, ( Revelation 17:1 ) not only by passing a sentence of condemnation on her, but by executing it, putting it into the hearts of the kings to hate and burn her, and utterly destroy her; and which is judging right, since it follows:

which did corrupt the earth with her fornication;
drew the kings and inhabitants of the Roman empire into wicked and idolatrous practices, and so corrupted and destroyed them in soul, body, and estate; (See Gill on Revelation 11:18) for this vision is contemporary with the seventh trumpet:

and hath avenged the blood of his servants at her hand;
shed by her, ( Revelation 18:20 Revelation 18:24 ) ( 16:6 ) and this being done in righteous judgment, is matter of joy and praise to the saints.