LD:
A few miscellaneous things. First, I concur with the timeline advice. Include everything and the kitchen sink. When the first twinge of attraction made its way to your consciousness, and why (i.e. -- what was it about this guy that attracted you), etc. If R progresses, your BH will likely start asking the same questions over and over. The timeline helps, and you can build it via your answers to questions that he asks.
Some betrayeds want to cross-reference it to stuff going on in the family at the time, so they can have a vision of the two parallel realities ("While I was taking our daughter to the dentist, she was letting him feel her up in his garage... When she got home later I felt something was off...").
Prepare yourself for what your reality might look like if one or both of you finds out you have herpes. First, what if you have herpes, but your BH does not? How will you handle sex? Condoms for the rest of your life? Even that is not a 100% protection. No oral sex on you, ever? Or, perhaps sex becomes too fraught and completely goes away. What then?
Second, what if you are infected, and you have infected your BH? I think you should bring it up before the results come back. Right now it's like the elephant in the room nobody is mentioning. Your BH will likely feel a very high degree of injury if that is the case.
On another point, I want to mention something that may come up: what you did, in terms of your A, was pretty, to be blunt, dumb. I realize that cheating involves a sort of "upside down" mentality where logic sometimes doesn't apply, but even through that lens it was dumb. The AP was cheating on his wife, which you knew. He had a kid in your school. So you knew he was a cheater, and a liar, and a man willing to come on to his kid's teacher (a wise friend once told me that you don't pursue co-workers or kid teacher because "you don't shit where you eat"). In other words, you had an objective basis to know he is a piece of shit.
Yet, despite knowing this, (a) you had unprotected sex with him, and (b) you shared naughty pictures with him in electronic format that he could put on the internet, or email to parents of your classroom students, etc. Put aside the fact that you were married. Even if you were single, if I were your friend, I'd slap you in the face and call you an idiot. What could you have possibly been thinking?
Now, here's another level. He was a parent of a kid in the school where you taught. If shit were to hit the fan, you'd lose your job, and possibly your teaching license. Again, "you don't shit where you eat." Again, what could you possibly have been thinking?
Another level. Your daughter attended the school. It was a good district that you worked in so your daughter could be in the school. So, if things went wrong, your daughter could also lose her ability to attend this school. Again, "you don't shit where you eat."
As the final layer, you did all of this stuff while married to your husband. Your husband is also the father of your daughter. Your husband also suffers if your daughter suffers. He also suffers if you lose your job. In other words, the levels of harm to your BH from your A go beyond the "normal" harm of an A. All of the collateral job-related damage you risked, that harm would flow to your daughter and husband as well.
I'm saying all these things, by the way, to help you, not hurt you. Trying to get your mind ahead of events on these issues, so you can think through your plan, your response, your healing.