I'm so sorry about what you're going through, emmasmum. I can only imagine the pain, emptiness, and emotional confusion you must be experiencing right now, and I will pray for you with all my heart.
It's true, the Bible says that divorce and remarriage is adultery. It also says that God hates divorce. Yet many people reason that a truly loving God would want them to be happy and blessed and fulfilled in life, so surely he must make an exception for their particular situation. This is a classic trick of the enemy.. First he injects a paralyzing sense of fear and entrapment, then he comes "as an angel of light" and provides you with what looks like a wonderful escape (usually another love interest). But the truth is that the corner you think you're backed into is nothing but a bunch of smoke and mirrors he's set up to trick you, and the "escape" is no less rigged. Too many married men and women fall into this trap, but you don't have to be one of them. You can be one of the few who choose the better way. Plus, if you truly care for this other man, you won't want to walk him down the path of adultery. It's not worth risking either of your souls.
When you and your husband were married, God joined you together as one and declared that nothing except death could rightfully separate you. This means you can never again be whole and complete without him. You
need your husband, and believe it or not he needs you too. This isn't a hopeless doom sentence; it's a wonderful part of God's design. God is never wrong by the way.

So this other guy really needs to be removed from the picture right away...not because he's "bad" or "evil" (I'm sure he's a very nice man), but because you both will be tempted to sin for as long as you continue to keep contact with one another. You must realize that God is calling you each in a different direction in life, then let go and have faith.
As for your relationship with your husband.. I would recommend Christian marriage counseling, or at the very least a good book on the subject. They can be very uplifting! But if that's not possible for whatever reason, here's what you can do..
First, make the decision to love your husband consistantly and pray for God's help in loving him. Love is a choice we
all have to make if we want our marriages to work, so you're not the only one who will struggle with this. Focus primarily on agape love, which is the same love Christ has for you. This love is very accepting, very steadfast, and totally unconditional. Emphasis on
unconditional. He shouldn't have to perform in order to receive agape love from you. He shouldn't have to do anything, really. It should just always be there as the cement that holds your marriage together, because agape love is about
commitment. Don't worry about romantic love or the feeling of being in love. That kind of love is a byproduct of a good marriage, not the foundation for it, and it will come about naturally for both of you in time.
Then, respect your husband and be submissive to him. Many women find this to be one of God's toughest commands, but it's also one of the most rewarding. Men are so different from women.. Their hearts are touched in different ways. In marriage, nothing touches a man's heart like sex and respect. God made him this way. He needs to know that he is admired by his woman, that she finds him attractive, and that he can satisfy her like no one else. According to the Bible, we should do this for our husbands whether we feel they deserve it or not. Like agape love, it must be unconditional. Your respect and submission will do a lot to raise his confidence as a man. A confident man is a happy man, and a happy man will be more willing and able to please his wife in the ways she wants to be pleased. It may take a long time before you see any results, but you must keep at it. Call on God when things get tough; he'll give you the strength you need.
I read a quote once that went something like this -- "The grass isn't really greener on the other side of the fence. You have to water your own grass if you want a healthy lawn." I think that's so true. As you go through the motions and begin to fight for your marriage, avoid all thoughts of life without your husband. Resist the temptation to think your life would be better if you were alone or with someone else. Also avoid thoughts like,
"This isn't fair. Why should I have to show him love and respect when he doesn't show me any?" (Love keeps no record of wrongs and it doesn't keep score.) Eliminate the word "divorce" from your vocabulary. Don't even keep it as a last resort in your mind. When you do that you're allowing Satan to stick his foot in the door and believe me, he'll keep pushing from there. Remember that Satan comes as an angel of light to deceive you. He's very good at what he does, so you'll need to keep your heart in check with scripture all the time. And pray constantly. I'll be praying for you too, and I'll bet there are others here at CF who are keeping you in prayer. You're stronger than you realize, sister in Christ.

You can do this, and I believe your story will have a happy ending.
Peace & love!