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By not reporting the assault and taking the high road, you are giving your spouse the opportunity to seek a criminal or a civil order herself against you. I don't know that she'd be willing to lie just to prevent you from charging her or from protecting yourself, but you don't have to lie. So why put yourself in a position where you cost yourself the very evidence you need to defend your position if she does file? You're right to be concerned and to want to get an order of some kind.
There are criminal and civil protective orders and in your state, you'd be eligible for either one of them. If you're interested in a criminal restraining order and your wife assaulted you on Saturday night, you can still report her to the police, have her charged with the assault and get a criminal restraining order, which would be granted virtually automatically as part of the criminal case.
If you don't want her arrested, you can still go on record with the police about the assault, so that there will be evidence that she did assault you, in case you ever need it. From there as a victim of a domestic assault, you would be eligible in Oregon for a Family Abuse Protective Act restraining order. You would obtain one by going to the Circuit Court in the district where the assault occurred. Tell the civil clerk there that you want to get a FAPA order filed against your wife. The form you need is a "Petition for Restraining Order to Prevent Abuse"
The emergency order will take effect once your spouse is served. If she wishes she can ask for a hearing which you would attend. You can find out more about the process and the proceedings on this overview here.
Just checking in to see if you need more help or any clarification of my answer. If so, please reply here on this question thread.