Singulair Anxiety Attacks, Part Time Job, Loving Child, Missing School, Life Path

I have posted a few times. My daughter started taking singulair 11-17-2003 and I stopped it 3-28-2008. She is the one that dropped out of dance and cheerleading, withdrew from old friends and family, headaches, stomachaches, missing school with this, depressed, anxiety attacks and CUTTING her self under her clothes. 6 months with a psychiatrist did not help. She is now about 80% back from the darkness. She is so much better and is such a loving child, She is not cutting, has a part time job, and has passed all her classes with 3 A's, 1 B, and 2 C's. BUT there are learned behaviors while in the darkness that still show up. Not every day but they are there. She has been pushed off her life path. I am hanging on to her with all my might and I know that I will get her through college and she will have the tools to be self reliant and happy BUT what could she have been if I never gave her singulair???? I can not help but feel guilty to what I have done to this child