That is part of the problem. You are looking for someone to tell you what to do each step of the way. However, you need to take charge. You need to determine what is the best way for you.
We can give you advice on what you should do, but we cannot live your life for you.
So far, it sounds like you have been a dutiful daughter and for the most part wife. Doing and accepting what others decide for you. I think rebellion may be part of the attraction that your classmate holds for you. Once you take control of your life, making decisions for yourself, I think you will see that the classmate is using both you and his girlfriend to get what he wants.
Can you answer these questions:
What do you want in life?
How do you get what you want?