As I told BBJ, l've lurked here for a long, long time, but I've done the "save the marriage" thing for my D for 13 years.
You need to stay on vacation, and if you can get your parents to join you and watch the kids while you get away on your own, all the better. Please remember, your parents have been violated too. It may be your marriage, but your parents have a right to their feelings. Don't see your mom as self-centered, she -- and your dad -- opened their hearts and souls to your H just as you did. He abused their love and trust too. It sounds like, over the years, they may have sided with him over you so they have a right to their anger. They thought they were doing what was best for you and your kids and now they learned other otherwise. They have a right to their anger and you need to let it be.
Oddly, my father was diagnosed with cancer prior to my major drama. Short synopsis. My family is eccentric but very, very close. We love and accept most everyone, but few get into our inner circle. For many years, my family adored my husband and they sided with him on many issues over me. After his 1st EA and our move to a new city, his shine diminished -- not because of what I told them but because of his behavior. In retrospect, it was a cycle. As a family, we love people. For the few we let in, we lacked boundaries.
At some point my H thought that he was total family and that his behavior was separate from my family's lives. The day my H spoke horridly to me in front of my D -- she was 14 and I had been silent for 11 years -- my D called my brother. My brother talked to her, but he was jumping onto a flight so he called my parents and one sister. Everyone was shocked at my H's words and tried to defuse the situation with me. I stood firm -- he was out. They tried to talk me down from my stance. I stood firm and told them enough was enough. They were shocked at what I told them about the past 11 years. After they heard what I told them about the last 11 years, they stood firm that he was out. When I floundered they told me to stand firm, he was out.
My dad was an amazing man. He was the last in the family to defend my H. He never spoke badly about others. His kindness can be measured by his funeral. At the age of 85 there were more than 500 people at his funeral. Yet, the night of the horrid words he said without challenge and riddled with cancer, "I'm tired and have no more strength, but I've seen H's meanness grow over the years and if you say he's out, he's out." My family then shut him out. My H was shocked at my families shut out.
We went to a MC. My H cried to the MC over the lose of my parents and the lose of my family. He couldn't understand why they would reject him. He told our MC, in tears, that my parents and my family were his only parents and his only family. He said my parents and family meant more to him than his own parents and his own family. Yet, he never directly connected my parents and my family to me. He told the MC he failed our D and he wanted to make good with our D.
In the end, I let him come home. I don't think my dad ever forgave my H before he died. It doesn't matter what my H thinks about my dad's forgiveness. My H has worked very hard to build a relationship with my daughter. Good on that because he let her down for way too many years. They have grown very close in the last year. She has gained so much from these efforts. For that I'm grateful.
Me, I'll probably be gone when she goes to college in 2 years. I think my husband thinks the same. If I could redo it all, I would have let him go 13 years ago when he wanted to go. But, I have no time to regret any of my choices. I have a life and I just keep moving on.