A very strange and harsh situation you are in right now.
is it possible for Polish government to revoke ones citizenship because of blackmails from one's spouse or her family members?
I don't think so. It is always possible to revoke someone's citizenshp, but definitely not on the basis of such trivial grounds.
Maybe it is good to seek advice from a family counsellor and/or a lawyer. Advice from random people on the internet can hardly be helpful or accurate in your case.