Welcome to PC, Jule03
I'm sorry to hear you've gone through this betrayal . I'm not sure the person who lied to you or 20 years will change in the matter of fe month.Youve been lonely for most of your marriage,striving to please him and prioritizing his needs .im not in any position to suggest next step,but I believe I would leave and begin a life ,where I could at least respect myself and not feel as a failure, better feel lonely when you are alone then lonely with a husband.
Peace and love to you