Is this a friendship or what?

I have an opposite sex women friend. We both are married. We become friends six months ago when we both happened to live in place for some time. thereafter our family knows each other. We both use to call each other at least 3 times in a day and minimum for 1 hour/day and maxi mun 2-3 hrs. I am sharing almost all my personal problem related to my unhappy married life to her and she use to give advice. she also share some of her personal matters with me. We talk about almost all under the sun. my wife know the above relation and she often quarrel with me for keeping her as friend . My friend know the same but she hide our contact with my wife and also with her husband.we call each other when her husband and my wife are not there.However we have not talked anything about love or sex. There was an occasion, that we emotionally hold our hands together when we happened to part after a long journey. some times we call even late nights. Whenever we get an opportunity to meet in any official meeting we manage to sit nearer and she use to come in my car and and come for Coffee with me on my request. But her relationship with her husband and kids are in good terms as i know. I haven't observed any sort of ill motive on her talk and we had enough opportunity to do any wrong if we want. she is a very good person, talkative and social and having many friends. But i don't know whether she consider me only as a friend or anything more than that. it is true that i have developed an emotional attachment with her. can anyone analyze it and give your opinion as to what is the relationship we have each other?