Thanks for posting your query at DoctorSpring.com
I have gone through your question in detail and I can understand what you are going through.
But unfortunately, modern medical sciences, has not developed any such test to identify if your husband is having sex or not. Among females, its possible to determine whether a lady is a spinster or is having regular sex.But same thing is not possible with males.
It would be better if you hire some detective services to keep a watch on your husband and give you some feedback,.
Hope this information was useful.
Dr.Srikanth Reddy MD