Get thee to a doctor pronto. You know all of the sleuthing that is now necessary. If you are not convinced that all is well, then ease your own mind and check things out.
Your list of possible scenarios for his re-entry into the affair sound very possible to me. I am so sorry, because it seems so cowardly, especially after you have clearly told him of your needs.
Remember, make the appointment first and then start checking things out.