Re: Moving on with his girlfriend whilst still living in the married home
You had a suspicion, you made plans to divorce, he showed you that you were correct and he was cheating.
I'm not sure what you were expecting to happen? Were you bluffing about the divorce to try and get him to come back to you?
Never use divorce as a bargaining chip. If you were bluffing, he called your bluff. Carry on with the divorce.
"If you deliberately plan on being less than you are capable of being, then I warn you that you'll be unhappy for the rest of your life."
~ Abraham Maslow