I am so sorry to hear you are going through this. Abbey and Kat have good advice. He's not going to make this marriage work and you don't want to live with a man that won't be your husband. He's not going to change. Let us know how things are going for you. Wishing you luck in your proceedings and piece in your heart.
If you were married in NC, you will have to be seperated for one year before you can file for divorce,so I hope for your sake this is not the case. Once a cheater always a cheater. I learned this the hard way after forgiving my x for a couple of infidelities during our marriage and then after all the forgiving he still left me for another woman at end.
If he has cheating on you already once, with your own friend(what a friend by the way)and you know he is currently trying to get involved with another woman and is not making any attempts in fixing things with you, My decision would be to file for divorce.
Please think about it very hard before making your decision and make one which you will be able to live with. Divorce is hell! First the legal portion and then the emotional and finacial part as well.