Fiance's Ex-wife is a psychopath I've tried everything now what?

so my boyfriend/fiance has been divorced for the past two years I have known him for 2 1/2 yrs. It used to be really bad she would har him, call him a ******, tell him lies about me, spread rumours about my life. After a year she simmered down to texting him prefusly about her dog about her van, false claims of abuse from her now baby's daddy. After that didnt work she begun to har me over facebook telling me about her past life with him and about all the things i shouldnt life about him. She really tried to taint my view of him so i blocked her out of everything. Now I just see her all the time dirving by my house or just driving down the road she likes to tailgate me, speed past and everytime i see her she tried to contact me via facebook or my fiance. I am fairly good friends with ehr sister (who is the nicest person in the world and dosnt much like her sister) so i know what she says about me.