I am so sorry that you are here. It sounds like your man is going through a crisis, i.e., death of his mother. Depression is the main ingredient of a MLC and it takes years to work through one. Your man is grieving for loss of his mother, but also the loss of the connection to his childhood.
As for the former girlfriend, they had a strong connection growing up and it appears that the reconnection has been sparked if he's calling her all of the time or staying at her place. Red flags are waving quite strongly over this situation.
Confronting him will do no good. If anything, it will push him closer to the former girlfriend. Your man doesn't care how you feel or what you want. Right now, he is running from everything and can't face reality that his mother is gone and wants to go back and revisit the "olden" days. You didn't break him, therefore you can't fix him...he has to do that himself.
You've been very generous in relocating and taking care of his father...but it's time to consider looking for a home care agency to come in and help his father out. I know that you feel a sense of duty to be there for his father...but it's not your responsibility to oversee his care any lon
My advice, start figuring out where you want to go and then pack your bags and leave. Don't threaten to do it because he will think you are just spouting off. Actions speak louder than words. You aren't married to this man and, as you can see, his moral compass is very much out of whack and his empathy chip is broken. Once this man is through his crisis (if he doesn't stay stuck), if he truly loves you, he will find a way back to you...but...until that day comes, you need to live your life to the fullest as if he won't return. It's time to put the focus back on to you and what you need to do to live your life.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
