It doesn't surprise me that your friendship is a trigger. When you only have one or two friends, you have more to lose. Betrayal is difficult when you have put your trust in someone and find out they lied to you.

Would your friend be receptive to discussing the matter? You deserve a lot of credit for wanting to repair the friendship rather than ending it. If your friend values your relationship as much as you do, she will sit down and talk with you.

You are not worthless. You are not the one who lied. It would seem to me that you are the stronger one. I agree with Roman. Talk to your therapist about the situation. Therapists aren't just for the initial problem, but also for the fallout that occurs as a result. It should be a place where you can discuss anything. They won't lie to you, aren't emotionally involved and are in a good position to help you work things out.

Sam2