I can understand your feelings–but don't let your confusion, your pride or anything else keep you from facing this situation honestly. If you don't, you will not only end up embarrassing yourselves, but you may hurt your chances of helping your daughter.
After all, your friends won't abandon you when they learn of your situation–not if they are true friends. The Bible says, "A friend loves at all times, and a brother is born for adversity" (Proverbs 17:17). You may even discover that some of them have been through similar experiences, and they can encourage and help you. The same should be true of other Christians. The words of the old saying are true: Christians aren't perfect–they are just forgiven.
The real issue, however, is what you can do to help your daughter. She alone is responsible for her decisions, and she must bear the consequences. Don't take all the blame on yourself.
At the same time, pray for your daughter, and let her know you still love her and want what's best for her. This relationship may well collapse; they often do. And if it does, she will need you more than ever. Most of all, she needs Christ, for only He can forgive her for the past and give her wisdom for the future.