Hello
Thanks for using doctorspring.com for posting your query. I have gone through your question in detail and I can understand what you are going through. \

The kind of superficial fluid filled swelling that you are talking about seems to be a vesicle. Now these vesicles can occur due to many reasons common reasons being:
1) Allergy
2) Viral infection

Allergies can occur to trivial reasons such as the latex of the condom that you have used or any Vaseline or lubricant or even the deodorant or powder that you wife has applied. Now allergies are self limiting and all you need to do is take some anti-allegic drugs like cetrizine and things should be fine.
The other reason could be viral infection. There is no need to hide anything from you as you seem to be mature to understand the facts. There is a possibility that it could be a sexually transmitted infection like herpes as well. In that case both you and your wife will need to undergo certain blood tests for herpes.

All said the allergy possibility is still on the top. At present what you should do is DO NOT BREAK THE VESICLE as it may get infected. Avoid sex until the lesion heals. Get the lesion examined by a dermatologist who can examine the lesion and identify whether it is allergic or viral infection. Then accordingly the treatment can be started. In either case the illness is treatable and there is noting much to worry. It wont hamper your sex life in any way.

Hope that helps, please feel free to discuss further.
Wish you good health,
Dr. Srikanth Reddy

Hello
Thanks for the follow-up query.
Latex it is most probably. It is self limiting. You may take cetrizine 5mg at night for few days but be careful with the sedation of the cetrizine and do not drive if you are drowsy.Other wise it will heal by self in 1-2 days. If not do show it to a dermatologist.
Hope that helps
Regards
Dr. Srikanth Reddy