I am crying at nights so that my father doesn’t see this

I am crying at nights so that my father doesn’t see this

Could you check my sentence please?

.
I cry at night so that my father doesn’t see it.
.

Why not, I am crying at nights ? Does at night mean every nights in your sentence ?

.
It is not a natural utterance. My sentence means ‘every night’ (‘every nights’ is also bad grammar.) You could use ‘every night’ if you wish.
.