I understand myself how serious this is - I remember once I had been mugged by some teenagers when I was out at 9:00 at the street beside mine. Luckily we could fight our way out, and literally for the week after that I came outside armed with a swiss army (insert object here) and semi auto BB (insert object here). BB guns, even if fairly harmless, they can deter an attacker, and especially if painted black, intimidate them.
My advice is to keep a BB gun because it is inexpensive, easy to obtain. Keep it loaded and cocked somewhere easy to reach. I have mine right behind me on a shelf, hidden by some books.
Oh and being chased by some drug dealers with a gun in complete dark, not fun.