Hi,
I am so sorry for your situation.
Is there anywhere in your town that do womens refuge? Quite often cities have places where women can go in confidence and they will help you to safely remove yourself from your marriage and they will give you a safe place where you can live or at the least they can offer you support.
I think there are also certain times in your life when you need to be selfish and think about yourself, try to maybe put your needs first and try to find any way you can to get out of your situation. Its really great that you manage to go on this site though, i am finding it very useful and a great support.
Lastly, your initial post was saying how you made this mistake with the guy, is there no possibility of writing a letter to him even and explaining your position? I don't know if this will seem weird to you but you could even use the feelings of love you have for the him to keep you going in your marriage and to keep you strong?