As for the 4 yr period, it is the time that the landlord can sue you from the date of the breach of the lease agreement. Once that date passes, the landlord can still sue you but you will have a defense based on statute of limitation.
If you don't have the money now, there is nothing you can do but hope that the landlord doesn't sue. If the landlord sues, you will then have to either pay or perhaps file for bankruptcy.