The first stanza is based on Yirmiyahu 30:16:
והיו שאסיך למשסה
Those who spoiled you will be spoiled
This translation follows Rashi there, who bases it on Targum Yonatan's וִיהוֹן עָדַיִךְ לַעֲדִי, which carries the connotation of a being defiled; innocence and purity violated.
Therefore, the second stanza now makes intuitive sense. It is based on Yishayahu 62:6:
כי־יבעל בחור בתולה יבעלוך בניך ומשוש חתן על־כלה ישיש עליך אלהיך
As a youth marries a virgin, your sons shall espouse you; And as a
bridegroom rejoices over his bride, so will your God rejoice over you.
Hashem is telling us that even though we have been spoiled, and violated, we need not feel ashamed. He, our God will be towards us as if we are still a virgin, He, our chatan, will rejoice in our union as a perfect, unspoiled kallah.
May that great day arrive without delay.
How apt, this question is asked during Pesach, which commemorates when Hashem became our chatan.