My husband stopped being intimate with me in every way!! What do I do?

My husband and I have been married for four years now and for the past three years he has stopped having anything to do with me intimately and sexually. We are sexual about every 17 to 20 weeks and it is killing me! I have sat him down and poured my heart out to him, crying and begging him to please tell me what is going on. The only thing he says is that he doesn't know what is wrong with him, but he just isn't interested in sex or intimacy at all. He has no impotency problems because we had that checked. The doctor gave him some Cialis, but he won't take it. We went to couples counseling once, but, he won't continue going. I am so in love with my husband and all I do is fantasize about making love to him. I cry myself to sleep at night. We sleep in separate bedrooms and have for almost two years! It doesn't bother him in the least. He claims that he is still in love with me, but he absolutely does NOT show it. He says he WILL start showing it, but he NEVER does. It is ripping my heart out. I don't know what to do. I am at my whits in! I am athletic and even had a breast augmentation to help to be more attractive to him, to no avail. I don't know what to do anymore. I have told him that I cannot take it anymore and that I cannot live with a husband that doesn't want me. All he says is that he will try, but, he never does. What do I do? Do I just give up? My heart is breaking. He is only giving me 10% while I am giving 110%. Please, please, tell me what to do. I have practically begged him!!! I am so tired of not being wanted. The neglect is making me feel so ugly...so unwanted. Please,someone out there tell me what to do. We NEVER had this problem when we were dating. Please, help me.... Desperate to keep my marriage.