adsj: My son was 10, daughter was 13 when their father told them he was "gay". Son refused to believe him, became really hostile toward me. Daughter was entering High School & focused her attention there, joining various clubs ( social justice, drama, leadership, among others).
It was quite difficult for me because I had set aside my own career to help him build his. I had expected that I would eventually have my turn to return to post-secondary school and complete my teaching degree. This did not happen because of the situation he stuck me in. The year he turned 40, he decided to quit the executive position he had worked toward for 20 years. Decided to open his own business; paid for this by refinancing (increasing) the mortgage on our home. Assured me that he needed to do this and as the co-owner, I believed him.
5 years later, he told me he "wanted to explore his homosexual feelings." To say I was devastated, would be an understatement. He had me believing I had no reason to live, because he had successfully "gaslighted" me for all of our 17 year marriage.
I got therapy, tried to get counseling for the children, which he opposed (no surprise) & succeeded in convincing them I was the crazy one.
Anyway, I was able to get a couple of daughter's teachers on board (confided in them) & they helped her tremendously. She in turn, helped her brother, even though he refused to live with us. (I am so glad I had always nurtured a strong loving relationship between them.)
It has been 19 years since his disclosure, and my daughter (31) & son (29) seem to be on track. No drugs, law-abiding citizens of whom I am really proud. Both are working in their fields of passion and earning good wages. When we visited on Mothers' Day, they joked that both are earning more than I (sad and true). But I do not feel bad, better they have a good future.
The most difficult thing for me back then, was to keep quiet about how their father treated me. He insisted on "letting me have the house", while he kept his pension-plan intact. At the time, I did not know how much was still owed on the house. And he did try to cheat me out of child & spousal support, claiming that his companies (yes, he had at least 2) were not making money & he'd have to declare bankruptcy. 
Fortunately for me, I had a friend who had been in a similar situation & she recommended her lawyer. I had to cash in some of my RRSPs to hire the lawyer. There was 1 meeting and while I watched the lawyer insist on his disclosure of finances, I actually began to feel sorry for him. It was all I could do to keep my mouth shut in defense of him. The Settlement Agreement was a good one, primarily for daughter. Son was not included, because he was living with father.
adsj, I realize I am speaking from the perspective of the wife who stayed home with the children. Your situation will be different. I know that when my parents split up (I was 16, brother was 14), I was very angry at both parents. Never got along well with mother, and felt betrayed by father. I wish my father had tried to spend more time with me, instead of focusing on his social life.
So as the "rejected daughter", I implore you to please set aside time to be with your children. Especially in this society which is increasingly hostile toward "straight people", it can be very confusing for them also. Let them know that you are interested in their "well-fare" for all of their lives. It will be difficult, because you will be painted as the bad, intolerant, homophobe, not only by their other parent, but by society. We & our children are the "collateral damage" of an ever increasing LGBTQ agenda.
I personally do not have a problem with people having whatever sexual preference they have. What I do have a problem with is the deceit involved. Recently, our daughter asked her father, "Why did you marry Mum knowing you were gay?"
He replied, "I wanted children."  Can you imagine how my daughter felt? Clearly he had no thought of her feelings. A lie would have been kinder to her.
 I am sure he knew that the very conservative British insurance company he worked for saw marriage as indicative of maturity & stability. And such a person would be excellent "executive /management material".
One thing I have come to realize is that all people prefer to associate with honest men & women. Teach you children that you are honest and want only their best. In closing, asdj, I am really sorry you have found yourself in this "club"; be assured that none of us want to be members. But we can support you by telling you of our varying experiences. It helps to know what options there are, and learn of some of the outcomes.
And please know that I am praying for you & your children, that you are able to navigate these rough waters. You are not alone, others have gone before.  My hope is that with the increasing freedom in our society, no more straight spouses & their children will have to endure this heartache.
Shalom=Salaam=God's Peace