What type of phone is your work mobile? If it's android then I know ways to block but there are also ways on other phones as well.lock down your Facebook to only friends. Take control rather than have her control you.
Lee, i get totally where your coming from but hey , blanking her is the best policy , once a rat always a rat , believe in karma . it may take a long time ? but what goes around comes around long term , i spent a year just under locked up and had a lot of time to think , many men killed their partners for various reasons in there , and i know they regret doing it . Hate and spite is dangerous , let the rat get on with it and you move on , just prey your child doesnt turn out like her !