If I truly loved my husband would I be in love with a second man?

My husband and I have been married for two years and together for eight. We met right after I had gone through a heartbreaking divorce and he became my rock. We fell in love but it was not fiery or passionate ..it was comfortable and safe. I have a fiery passion in my first marriage and truly felt he was the love of my life and I honestly did not think I would find that again. There is something lacking with my husband.. fun, excitement,everything. I feel as though I have outgrown him and I feel wretched about it because he is a truly wonderful man and a wonderful husband.
I did not realize I was unhappy until about six months ago our neighbor hired a man to come work for him. We are in a very remote area and work on a ranch so there are not many people around and Luke was like an oasis for me. We became very good friends very quickly trusting each other enough that we felt safe telling each other just about anything. We spent time together and my husband was often with us and they have also become friends although not close friends. My husband trusts me and I am emotionally betraying him.
The three of us often do things together and Luke and I have both recently admitted to each other that we have fallen in love.
I realize I cannot carry on like this.. it feels like Luke has woken something up in me that has been asleep since my divorce. I did not know I could feel like that again. Very poor excuse but nonetheless it is exactly what's happening in my life. I married a man basically for security and safety and I wonder if I was ever truly in love with him. It's not fair to him and I do not want to hurt him but I am afraid I am going to destroy him. I don't want to but I cannot live a lie anymore. I feel guilty about it but I more feel guilty that I don't feel guilty like I should if that makes sense.
If I truly love my husband I would not feel like this for somebody else. Is that right? Can you love two people at the same time?
I am terrified to start over again and I will not leave my husband for Luke. I will leave for me and if Luke and I work out afterwards that's OK too.
Has anybody else ever been in this situation? Please tell me how yours worked out.. I feel so alone and like an awful human being.