Oh, Oh

I did an Ancestry DNA test. A man roughly my father’s age came up sharing the same % of DNA that my mother has with me. I had no idea my mother even did the DNA test because has never mentioned it. The I contacted the man who was listed sharing my DNA with he and I talking via text. Without a question he is my father and I have four half siblings through him. The problem? The man I have been led to believe is my father, isn’t. This man told me that he and my father were best of friends and that my mother and he fucked a couple of dozen times behind my dad’s back. When my mother got pregnant with me she refused to leave my dad and told my bio father she wasn’t sure which of them got her pregnant. Well now we know.
My younger brother and sister don’t know anything nor I am sure does my dad.
Yes I call him my dad. He’s been a real blessing in my life, loves me big time as I do him and I’m sure this truth would kill him and perhaps blow everything up.
No idea what to do.
I would like to meet my bio father and half siblings and he is definitely for that.
What would most do?
Do I talk to mom about this?
Doesn’t my dad deserve to know?