Find the time to read this:
http://www.nononsenseselfdefense.com/
Then do what YOU think is best.
One more thing. I don't trust the police to make the streets safe, but for some PARTICULAR problems (ceratin persons, or certain areas, at certain times), you should be able to get some cooperation and protection. If you go to the local police station, introduce yourself, let them see you're not hot headed and realise you have a REAL problem (if you do).