I wasn't being sarcastic - family ties in law could mean one of many things. It could link to wills, estates, domestic violence orders, parental responsibility...so in order for us to help you, it's necessary for you to be clear.
I'm not sure how a stat dec would help you 'cut family ties'. A stat dec is simply a formal document stating something is true, but it doesn't impose any injunctive obligations on anyone else to stop them from contacting you.
The only legal avenue available to you, really, is a protection order of some description. However, if there are property implications or children's matters involved, a protection order won't relieve you of any relevant responsibilities you may have in those areas.