What should I do with my husband who always cheats on me?

When I found my husband who has cheated on me from the phone text messages,or his email with other women since last eight years, my heart is broken, I cried a lot, but he never admitted it. I forgave him, after three to four months, it happens again. Because of his job he has to travel or stay another country for sometimes, eventhough he is sixty years old, twenty four years old than me,I love him but I never feel he respects me that I am his wife. Especially I found out today there were two different women staying with him when I was not around him here in Singapore during last four months. he did not admit again that the two women stayed with him and made some excuses for me to believe, I know he is lying.

What should I do? I am so sad now.