To contact or not to contact ...?

Hello, My story is a little different than most that I have read on this site. I am 28 years old, always known of my adoption, and have known my bmom all of my life. Though she made the decision to give me up she could really never let go and my amom is the type who believes family is family and there is no escaping it. They have had a good relationship over the years, a sincerely trusting one. When I was born, they were all military and in a different country at the time. We returned to the States at my age of 3. I have pics with both bparents as a baby and toddler. I bonded with them. They saw me grow, then still let me go. I received one card from my bdad when I was 7, wishing me a Happy Birthday. My amom always encouraged contact and they still live in the home they owned 30 years ago. Now ... my dilemma is around my bfather. I have known his whereabouts for nearly six years. He is married, looks happy, and has a daughter that looks a great deal like me (and my 9 year old son). She is young. I made a conscious decision, when locating him and finding out about my half sister, to not contact him. I have always known (or at least been told that) my birth mom agreed to adoption because he wanted abortion. I'm now happily married with three children of my own. At the beginning of this year I began having some severe health problems that are virtually unexplainable. I need my medical histories. I'm very concerned that I may disturb his life unequivocally if I were to contact him, however, I'm only asking for relevant information that can be pertinent to my health and the health of my children. I will not ask for a relationship with him nor to ever meet them. I can accept and respect his decisions made so long ago. So, I need advice from folks who understand. Am I asking too much ... or should I even ask at all? What are your thoughts? Thanks in advance for any insights that you can offer.