Ah, the desperate need to freeze crème fraîche. It's ugly for a time, but then the symptoms pass.

You face the same difficulties freezing crème fraîche that you do with whipping cream, sour cream, and yogurt. The water, which has been evenly dispersed throughout the solution, separates to form ice. When it thaws, it is difficult to mix everything together as thoroughly as before. Consequently, whipping cream is unlikely to whip as well or at all, although most people find it perfectly acceptable for use in cooking. Sour cream and yogurt are likewise equally tasty, but you might prefer to cook with them rather than make dips, where they might seem a bit sloppy.

Crème fraîche, which also can be whipped like whipping cream, will likewise give up that talent upon freezing, but you will probably be able to mix it well enough after thawing for most any other crème-fraîche-specific use.