I'll tell you exactly how this will turn out, because it happened to me last week.
Your beer is going to separate. The heavier part of the beer, i.e. the part with less water, will sink to the bottom once the beer thaws. For a dozen or so pours, it will be like drinking a barleywine. Then it will slowly mellow. I shook my kegs a good amount to try to mix it up, but it won't ever mix.
Your beer isn't ruined, but it ain't gonna be what it once was.