I apologize for the double post but here is the final product.

I am writing a letter to apologize to my principal for arriving at school intoxicated, but oblivious.

I need a grammer EXPERT to point out any wrongs in this letter please, I also want the letter to sound truley apologetic and not sarcastic,aggressive, or defensive.

Dear Mr. Gray,
      This is a letter from  xxxxxx, I am a student who attends the Behavioral Intervention Center that you manage.

I am writing to address a recent incident I was involved in, and apologize for it.
    I assume you have been informed of the situation that has occurred Friday Nov. 20, when I arrived on the premises allegedly intoxicated. I had not taken anything that morning before I arrived, however; the night before I had taken two, .5mg Clonazepam. I was not aware that the effects would the length that they did. I had assumed that the effects have dissipated by that morning. Albeit I was oblivious to them, they had not at the time.  I promise with highest regards to you that it certainly was not an intentional violation.
    With this letter I am expressing my deepest regrets and apologies for arriving on campus under the influence, and I request with consummate respect for your authority to please take my behavior at BIC to date into consideration. Also please consider the fact that I have been in transitional school since the beginning of October. This has created some very stressful emotions for me that I have been working hard on controlling. During all of my time at both BTC in Granbury and BIC here in Mansfield I have worked really hard to leave the Center, and just get back to regular classes. I respect  your authority and know there must be consequences, I am just asking if there is any type of  consequence that would not involve extending my time in BIC that it be considered. I'll stay after and help clean the building, remain in level 0 for the rest of the sentence, or do extra school work if you like. I just want to get back to school. With any decision that you make in response to the incident, positive or not, I assure you this type of thing will never happen again.

                                                                                                                                                      Sincerely,
                                                                                                                                                              xx