I don't know that any of us could truly say what the outcome of your case could be. Unfortunately, the proper answer is "it depends": it depends on the prosecutor, it depends on the judge, and it depends on the police report and what the officer noted that you may not have written above. The refusal of the FST and breathalizer does remove ammunition from the prosecutor. Typically, if the prosecutor can show someone was stopped validly and within two hours of the stop, had a breath result of .08 or above, that's a DUI. However, when there's no breath test, the prosecutor has to change tactics and prove that the driver was "appreciably affected" or impaired due to alcohol or drugs. This can be done via testimony as to driving pattern, FSTs, demeanor, speech, physical appearance and so on. Here, you declined to do the FSTs (which I always suggest-- they're voluntary and there's no reason to prove the case for the state by giving them more ammunition). There's no observed driving pattern. Depending on weather conditions, you may be able to get across that road conditions were slick. There's no breath test. These are in the PLUS box. But in the MINUS box, there's the fact that you had an accident AND that you had been drinking. The "unknowns" at this point: what you may have said to the officer (admissions re: alcohol), the officer's observances re: odor of alcohol, physical appearance, and balance/coordination, whether there were any unusual behaviors and/or changes in mood, etc.
There is no "usual sentencing" in Washington on a DUI. Sentencing varies from court to court. If this is a first offense, you may be required to only do the minimum: one day in jail, $866 fine, alcohol evaluation and follow up any recommendation, Victim's Impact Panel, one year ignition interlock device, and (because of the refusal) one year DL suspension. But jail can be anything from the minimum up to one year in jail; the fine can be anything from the minimum to $5000. I wouldn't estimate a great chance at dismissal, but a reduced charge or diversionary program is possible. All this depends, of course, on your prior record and what the police report indicates for this incident.
My best advice? Get a copy of the police report and seek a consultation with a DUI attorney. No one should attempt to handle a DUI case without counsel.