A very high-level martial artist once gave a seminar about this. Know what he said he would do if mugged for his wallet while w/his family?
He said he would hand it over, no questions asked. Ask any cop as well, they will tell your BF the same thing. Only fight if you are being physically attacked and you cant run. In this case, you fight for your life holding nothing back. Kill them if you can. Once chance. Ichi go ichi e.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh