Paula, I am glad you are sending the card. I think they will see this as the accident and they have been on your mind.
As for the AP issue.. psh.. you are a rock start teacher and you know it. Personal experience, sometimes they stay longer to avoid the office, sometimes they see you are not at your best and stay for support, sometimes they "feel" getting up will distract the class. Its not always a bad thing. Observations are just a snap shot anyway. They KNOW what you are like on a daily basis and they KNOW we teachers are human and have "off" days. Don't borrow trouble.
I hope the issue with the friends wife is resolved and does not lead to more drama for your already aching school.
Its great your son has opened up to you. I dont have any recommendations, just remember, parenting is not for the faint hearted.