You have to back up a bit more. She's talking about the following comment [censorship mine]:
I have herpes and Doe has herpes. Means I can [censored] her bareback
This comment implies that since they both have herpes, he may have unprotected sex with her, to which she replies
just like HIV, herpes has multiple strains, so there is still a lot of risk of transmission. That, and no: you may not have sex with me, I did not consent. My intent is to educate.
In this case, she is stating that he is wrong to make the assumption, and gives reasons why he is wrong.
That refers to the "risk of transmission" from the previous sentence. That's Reason 1.
"I did not consent" is Reason 2.
"you may not have sex with me" is basically "you're wrong". (having the no: in front further emphasizes that he is wrong)
And the and links it all together.
The "That, and no:" could have been replaced by Also and kept the same meaning.
[...]there is still a lot of risk of transmission. Also, you may not have sex with me, I did not consent.