Madam Shalini:
Do not hasten to come to the conclusion that your husband is a cheat. There are people in this world like Mr. Nagarajan who probably think about the role of s*x as a bad thing. We all, particularly in India grow up without knowing anything about s*x from "respectable" aources. If at all we know or fancy most well- bred children believe that though s*x may give pleasure it is a bad thing, which only bad people engage in and certainly not their own parents. Our religious literatures, except those of Islam, also preach the the virtues of celibacy.
Most probably your husband was brought up in such surroundings that he believes s*x is a bad thing. It is also possible that he lacks in libido. It may be a conditioned trait or may be of some genetic causes. But in any case it may be possible to make him s*xually responding. What is his opinion on p*rnography? Is it possible for you to expose him to p*rnographic literature?
Also you say that occasionally he has s*x with you. You should make best use of those occasions to make him want more of it. There are also specialist counselors on the subject. He or she can be an American or an Indian, because s*x is same across all cultures. First you meet the counselor alone and state your problem. Then you take him with you.
I believe that this problem can be solved. Do not lose heart.