Haier, thank you for telling us your story. I'm sorry, too, that you are going through this. I do not have a difficult marriage but I had a difficult blended family and something like what you describe happened to me.
My father married my stepmother when I was five. My stepmother had one daughter, 13 years older than I am and I have three brothers, all older, I'm the youngest. I grew up thinking I had a "whole" family. Then, in 1992, the day after my 42nd birthday, my father died (my mother died when I was 3).
Everything changed from then on; my stepmother leaned on her daughter and her daughter's children and I was just an "also" daughter, expected to be there and help but with no real role (not the oldest or "hers"). My step nieces and step niece-in-law :-) had more say and were more at home with the situation than I was. I was very confused and had to enter therapy again because my mother had been sick all my life and then died and now my stepmother was becoming extremely senile and my 40+ year old fears of "who will take care of me?" re-surfaced when I was the one supposed to be helping take care of my stepmother. My stepmother's and my life together as I grew up had been very difficult and abusive so there was that, too; my father had been an officer in the Navy so my stepmother was treated as his wife, my father being part of "my" life, not hers! It was very confusing to me as she was treated in the same hospital that my mother died in and all the old thoughts, feelings, experiences of my very young 3-8 years old life resurfaced and there was deja vu I didn't know/remember existed.
When my stepmother died, it got even worse. There was nothing holding me to my stepsister and nieces/nephews and that whole world anymore and I continued confused. Until last year, I was the only one invited to my stepsister's Christmas dinner party (my brothers have all gone their own ways and my oldest brother, with whom I "identify" the most, was the family black sheep, least liked by my stepmother and other brothers and not invited anywhere although he invited me to his home/parties, etc.), her second husband is dying and last year I was called and told her party was only going to be for her immediate family (obviously that means I'm not considered her sister?).
It's difficult to make adjustments when our lives are shattered but, eventually, all lives change and loved ones are lost. It's even harder when, as for us, the "basis," root of our lives, seems to change and we find what we thought was true for so long (big, happy family) was not true and we were, in a sense, fooling ourselves in thinking it was.
If I were you, I'd try to be glad the "other" shoe has dropped and you now know the situation. It is incredibly painful but there are possibilities, as with all change. You are a bit freer to learn about and be yourself, you don't have some man's clothes to iron anymore, you can read a good book in that time, or anything else you might discover you would like to do/try. You don't have to keep his schedule, you can arrange your time to better suit you and your girls, can become more relaxed and flexible because you don't have to consider someone else at the moment.
It's a shock! Don't feel bad about yourself and how well/poorly you feel you are doing; think of it like a train wreck :-) and allow others to help you if you can. Maybe join a divorce group or a "loss" group, take some personal interest courses or something see if you can start to build on this new plot of land? I suggest a good Southern exposure :-)
TLC Home "Why is southern exposure so sought after in the city?"