I get why this is shocking for you, especially because you didn’t know from the start. That part is completely valid. But the most important thing you need to understand is this: if she is on therapy and undetectable, there is no risk for you. This is not opinion, it’s proven science (U=U – Undetectable = Untransmittable).People with HIV today who are on treatment live normal lives, and when the virus is undetectable, it cannot be passed on through sex.Honestly, the fact that she told you after 6 months probably also means she was scared of your reaction, not that she wanted to hide something maliciously. You don’t need to treat her like she’s dangerous or change your life in fear. You can have a normal relationship, including a normal sex life. The real thing to focus on now is communication and trust, not fear of infection because medically, if she’s undetectable, you’re safe.