Hello Ragdollkitty
I sympathise I have a cat that can be "bossy" though he does not attack for no reason merely box our ears if we are not giving him the attention he thinks he deserves!
I would not advise getting another cat in the hope it may resolve the problem. You may want to check with the vet that there are no health problems and you may find a leaflet of the FAB website useful. Go to the pet owners pages, look under leaflets and read the one on nervous and aggressive cats.