You have been treated (dramatically over treated) for every STD that could possibly cause the symptoms you describe. You also have been reassured by your doctor (two of them, if I correctly understand the story), which is always more reliable than the advice from a distant online source like this, no matter how expert.
To your specific questions:
1) Prostatitis often is a "wastebasket" diagnosis, a name docs often put on urinary symptoms in men when they can't come up with a clear diagnosis. It's not an STD. Your symptoms actually are most consistent with the male chronic pelvic pain syndrome. If you google "chronic pelvic pain syndrome", you will find a lot of information. The Wikipedia article is especially good. As you will see, CPPS used to be considered a form of prostatits, but no infection is involved. It's often just a manifestation of anxiety.
2) If you had an STD, the antibiotics would have cured it, making the tests negative. Antibiotics do not make the tests negative except by curing the infection.
3) Clearly you don't have anything from that sexual encounter and probably never did. If you received the initial treatments before you had sex with your wife, it is not possible that you infected her.
4) About 80% of newly infected people have positive HIV tests at 3 weeks. But your chance of having HIV is close to zero, given your overall story and the reassurance you were given by your commercial partner.
You're fine. Let it go. You absolutely have nothing that can ever harm your health or your wife's. But of course continue to work with your doctor if your symptoms persist or you remain concerned.
Please no "yes but" or "what if" follow-up questions. There is no information you can provide that could change my opinion or advice.
Regards-- HHH, MD
Thank you Doc no "yes but" or "what if" only a thank you for your consideration and time. This helps to ease my anxiety and I may perhaps get some sleep this PM and maybe just maybe not be an idiot in the future.