Are you sure the rose has spider mites? Roses do go dormant in winter; they have to to survive. But you need to keep them someplace cool and the soil barely damp - watering once a week may be too much. The warm temperatures of your house are definitely too much. Spider mites like dry air but wash off easily. A better remedy would be to wash the plant every time you water. Bonide granules added to the soil will also help if you can't get rid of an infestation any other way.
You live in Zone 5b and miniature roses are hardy to zone 4. Although plants in pots should be hardy to 2 zones below yours, you could keep them in your garage or shed for the winter. They would be much happier.
