I meant to say that a psychological explanation isn't the only possibility for your symptoms. You are at an age when many men start to have urinary tract symptoms due to an enlarging prostate gland. Conceivably that could explain a sense of impending discharge, so see your primary care provider if that symptom persists or worsens, or if you start also having increased urinary frequency, urgency, or substantially slower flow of urine. But STDs don't cause such prostate problems and you need not mention your nonmaritial experience to your doctor (although you should not be untruthful if you are asked).
Welcome to the STD forum. I'll try to help.
The only STDs that cause urethral discharge, and the majority that cause vaginal discharge, are due to bacteria -- chiefly gonorrhea and chlamydia, plus several others that cause nongonococcal urethritis (NGU) in men and sometimes cervical infection in women. None of these persists for 5 years without symptoms, especially in men -- probably they don't persist more than a year. And as your own question implies, the possibility of persistence is even lower in people who have taken antibiotics for other conditions. Further, numerous non-STD problems cause genital in women -- indeed, STDs are much less common than non-STD explanations for discharge -- and the diagnosis of UTI is pretty straightforward and unlikely to be wrong. Therefore, there is no realistic chance that your wife's genital problem (whether really a UTI or something else, such as yeast infection) reflects an STD she caught from you; it is unrelated to your nonmarital sexual adventures 5+ years ago.
As for your own symptoms, there is nothing in your description that hints at any STD. Certainly sweating isn't an STD symptom -- and a "feeling" of possible penile discharge doesn't sound significant in the absence of a visible discharge. I see no need for you to be tested for STD. Finally, whenever a person suspects his or her own symptoms have a psychological origin ("Could all this be in my head because of the guilt?"), usually that is exactly the case.
See a health care provider if you remain concerned, but don't worry about any STD as an explanation for either your symptoms or your wife's.
Best wishes-- HHH, MD