I'm trying to bring democracy to two sicilies but after i become a democracy i get event that makes me presidential dictatorship and that's not what i want. Is there a way to stay as a democracy or is two sicilies supposed to be a dictatorship?
You have to have a non-extremist party in power. For example conservative, liberal, socialist. Democracies that have extremists in power will become a dictatorship. To get a non-extremist party in power, you have to first allow all parties, and to prevent becoming a democracy to soon (i.e. before you have been able to change the ruling party), you should remove all voting rights. Wait a while and you will get a two-party system. Now put a non-extremist party in power, and then allow voting again. A while later you'll become a democracy and stay that way.
i heard that having a conservative in power turns u into pres. dict. easily.
No only with reactionary/anarcho-liberal/fascist will a democracy become a PD. With communist you become a proletarian dictatorship. All other ideologies are fine.
then if such extremist party won the election, then it all means bye bye to republic....
Yes exactly. That usually happens when pops have high militancy. Or when you have chosen populism in the "populism vs establishment" event, and an extremist party has views that best match the people's issues.
then is there is anyway to revise it back to Democracy?
Yes, check post #2 in this thread.
edit: or did you mean when the people choose an extremist party once, they'll do it again? This will likely not happen because the government changes (democracy->pd and pd->democracy) both decrease militancy. You can also try setting voting rights to wealth. Or when things are hotly debated somewhere, try to choose the views of a non-extremist party.