1) it is better to call off engagement if you are not compatible
2)return all gifts received at time of engagement
3)you cant be forced to marry her if your fiancee is highly suspicious in nature and keeps on spying on you .
4) your fiancee needs psychiatrist treatment . convince her to visit a psychiatrist .
5)send her email mentioning the reasons why you want to call off your engagement .
6) in the event she files any case contest it on merits