1)
Why does it say "Kol Zos"?
1.
Radak: In spite of all this hardship that came to us [we did not forget You, even though we see the Goyim's serenity and our Galus].
2)
Why does it add "v'Lo Shikarnu bi'Vrisecha"?
1.
Malbim: We did not forget You in the heart, and we were not false to annul Bris Milah and Shabbos at a time of Shmad (decrees against Mitzvos).