Nothing is impossible, though.
If nothing is impossible, then "everything is impossible" is possible, in which case, nothing is possible.
how is "everything impossible" if "nothing is impossible"
shouldn't it be "everything is possible" if "nothing is impossible"?
it's not a paradox really, is it ?
It's a self-contradiction. See
here. Specifically:
"In classical modal logic, a proposition is said to be possible if and only if it is not necessarily false (regardless of whether it is actually true or actually false);"
From this definition, "everything is possible" means "everything is not necessarily false", which is false, since there are necessarily false statements (contradictions). Thus, "everything is possible" is a self-contradiction.