"I don't really know what's normal in relationships regarding STD disclosure" - I can clear this one up. You disclose it to your partner.
However embarrassing, however ashamed you personally may feel, even if there is a possibility of that person turning you down - you tell them.
If you are carrying a virus or a bacteria that could reasonably/probably impact the other person's health and wellbeing, you tell them. It is about informed consent.
Transpose it to another situation: if you had a cold and a friend invited your over, you'd probably say "I've got a terrible cold and I doubt you want it too". If you had a coldsore you'd say "no kisses, I don't want you to get a coldsore".
He has recognised there is something wrong, saught treatment, and not given you the information that would allow you to make a decision about your own health and your desire to continue an intimate relationship with him.
I know you have a lot on, but in this situation I think the bigger risk is minimising his betrayal rather than "making big decisions". PS. You have a lot on, and he is not even being supportive or listening to your concerns. You can do 1000x better than this idiot.