Crystal, i had a similar situation as you, in my case i left the house after trying to stay on for 4 months and it was torture, facing him and his lies, not knowing what to believe in, it was hard, so i understand what you are going through now.
When i discovered my ex having an affair with a mainlander colleague,i was 35 yo too, and with no kids.
Its not a strange combination, couples nowadays have kids later and there is nothing strange.
I am waiting for my last ancillary hearing, and hopefully conclude my battle for a justifiable distribution. Wish you and me luck, i am sure the best is yet to come!
You can PM me if you need any help.
cheers!