I don't think there is redemption for cheating especially because of a misunderstanding or just because it's a marriage of convenience.
If Arnav is ready to hurt her back then maybe it's not actually love
I really would like khushi to not forgive Arnav if he actually cheated but then again it is your ff and you decide how it should proceed.
Based on what I have read so far I know the redemption track will be super hit.
Loved this story and I hope that you continue soon and please send me a PM when you update