From your post it seems that you are suffering form an std. I cannot judge you for being unfaithful. However, whatever you did was not right. So your results for the std came positive 12 weeks later. That's kinda a long period. And if it was protected, why the infection? Concerning your wife. I don't think if you are supposed to worry that much. Women tend to have delayed periods. It is not because that she has an std. Some can even have a 1 months delayed period and it is not like they are pregnant. However, I cannot assure you of this. I am just speaking for a general view. Some cases might be different. As to your fears, the only way to assure yourself is by going to the hospital. Check if your wife is infected. Or it might be that she is pregnant. I really cannot draw conclusion that soon. The final answer lies with the doctor. If yo are afraid to tell her to go get tested. Then maybe you can wait longer. The time will tell you the results.