Oh sure she gets mad because what she is doing is wrong. I mean really think about it if it was right she wouldn't care what we say here. We may be strangers but unfortunately have something in common. We have been through this.
Let me tell you a story about my grandpa. He was cheater. He walked away from a wife that loved him and two children. He was insistent on the divorce, needed to find his happiness, other woman wasn't to blame for this, blah, blah. Same old story of the cheating spouse and that was like 44 years ago. The kid's were teeangers (my dad) and I think they suspected what happened but grandma didn't tell them. But when they got older and they asked she did tell them the truth. You know what they have no respect for him. They love him and help take care of him out of obligation. But let me tell you their hearts aren't in it. They can't even stand the thought of him living with any of them. They will visit but the thought of him there all the time. Now their mom the one that wanted an intact family and was good and pure they would do anything for. They love and respect her so much. So even into adulthod divorce affects you. It changes the way you feel about your parents when they do it. If I were you and she is insistebt about filing I WOULD file and get her on grounds of adultery.