The safe part of Charlestown is the very expensive, yupped-up area (in my humble opinion). The outlying parts and projects are very townie and not a place for the OP, I think.
Davis Square in Somerville or anywhere along Mass. ave. From Harvard Sq. to Porter and onto Davis would likely be a fine place for a 39-year-old woman who wants a lively life after work. Yes, you'd expire in Milton. Not ...