Avoid any confrontation whenever possible: the fight you always win is the one you were never in.  Almost all attacks are avoidable if you do not become complacent to your surroundings.  For use of force to be justifiable it must be necessary and reasonable, and the threat itself must be unavoidable and imminent.  Justified force must stop once the threat ends.  

Survival is always a fair game no matter how dirty you play.  Your attacker will not give you any advantage or dignity while attacking and violating you, so you must be willing to respond at that same level.  Remember that your attacker made the decision to play with fire by attacking you, so if they get burned that’s their problem.