The problem appears to be that while you haven't provided them with the full amount they've demanded, you also haven't provided them with what you normally pay every two weeks, correct? If so, they can certainly send you the three day Pay or Quit notice which is the FIRST step in the eviction process.
This is a civil, not criminal matter which is why the police won't touch this.
It is also important to remember that your roommates (who are acting as your landlords as they are taking rent from you) can't evict anyone. Only a court can grant an actual eviction. For them to (for example), box up or toss out your stuff, change the locks, refuse to let you in, etc. WITHOUT A COURT ORDER GRANTING THEM THE RIGHT TO DO THIS would be an illegal eviction and would open them up to, well, getting their socks sued off of them by you.
The steps toward eviction for owed rent typically follow this pattern: 1. notifying the tenant with a Pay or Quit notice listing a specific number of days that the issue has to be remedied followed by 2. filing through the court system for the actual eviction if the demand has not been remedied.
If they file, you will be notified of the court hearing and would be able to tell your side of the story to the judge. In this case your side would be that the verbal agreement was for your share of the rent to be paid by you in half installments twice a month and that in October and November you have honored this verbal agreement.
I hope this makes sense...
Gail