Need advise on how to handle my prob?

Hi, I am married with three kids, aged 15, 12, and 10. My hubby is involved in a realtionship which i found out and now he told me very clearly that I have to accept it or if i dont i have to leave him. I know my hubby loves me and his chn. He is obligated to this women bcos she is supporting him financially and he is also responsible for her mariage break up. I have lost my morale, my communication with him a we cant be loke before, he goes out with her stays with her and neve came back home and yet i am holding on bcos i was a housewife all the while and me and my kids needs his support and not bcos of money i am with him its just simple i dont want to have a broken marriage, so i have to accept it right. The pain and the tears i shed everyday is very tortourous, i am very lonely as i dont have friends and always alone. I feel like running away somewher but nowhere i can go thinking of my kids. My hubby has no resoect for me he said this to me that i am dependent on him i am not sup