With Matthew left, Robin was the only one in the Gotengo, he guided the ship towards the Mothership.

Xillian: Controller! GDF warship heading straight at us!

Controller X: fire everything! don't let it crash into us!

the Mothership fired all it's weaponry at the Gotengo which had rerouted all power to shields and thrusters.

Robin opened up a comms link to General Irons and all other GDF/Monarch operatives, with that he leaves his final message

Robin: hello, everyone, this is Ex-Commander Robin Atkin Downes, this is my final message to all of you: you all were right, about me, the real monster was me all along, my men died because of me, families suffered because of me, this world belongs to the Kaijus, not the humans, I have nothing to live for but my anger and hate for all Kaijus, so i'm ending my life by doing the right thing for once, taking out the Xillian's controller! It's over, goodbye *ends transmission*

Xillian: it's no use, the warship's coming right at us!!!

Controller X: NNNNNOOOOOO!!!!!!!

The Gotengo rammed into the Xillian Mothership, blowing it all up, taking the Xillians, the Controller and Robin with it.

the explosion could be seen from Earth, the K-Squad, Monarch and GDF watched it all, it was over the Xillians were defeated again