Aurora: There are many things you can do, but a trip to the vet is of the utmost importance.
Check again for any physical problems, things can change, even over a short period of time. And if it is behavioral your vet can help you with that as well, there are tips he/she can recommend you follow through with, there are medicains and behaviorist you can consult.
I can tell you, she probably will not stop peeing in that spot until you douse it in something like Natures Miracle, just a simple cleaning in your washing machine will not get all the smell out, cats noses are much more sensitive to smells then ours. Also, invest in a plastic bed cover you can put under your sheets in the mean time to save your matress, it will reach a point, that she pee's there too much and you will have to throw your matress out.
We don't know enough about your cat to say what the behavorial issue might be, or if she even has one. So make an appointment with your vet asap, and you can keep your cat in one room (not your bedroom) a laundry or bathroom some place with out carpet or rugs, and keep her in there, provider her with food, water, toys, and a litterbox, this might retrain her to only use her box.