Sorry about your situation. I believe your first step would be to review the Landlord Tenant Act of Washington. I've attached a link to it below. By reading over the relevant parts of this, you'll make good use of your time with either the Tenant Union mentioned by Jason, or with an attorney.
You do have rights, but so does the new owner, so by reviewing and discussing this with the right people you can be prepared for whatever happens next. Best of luck.