They will probably file a note on your credit but they may also sue you for damages and/or return of the property. If they sue for damages they could put a lien on your income to ensure payment or prevent you from getting a loan in the future. If they sue you for recovery of the property it won't be stealing but failure to return the property will put you in contempt of court, which carries similar penalties.
Bottom line, if you broke the contract and want to keep the furniture you need to work out a settlement with aarons. Keeping the furniture is going to end up costing you a lot more than it is worth.