My ex-wife called asking to be my plus one to our son's wedding since he didn't invite her.

My ex-wife called asking to be my plus one to our son's wedding since he didn't invite her. Six years ago, my daughter was 12. She came home early from soccer practice and caught my wife in the bedroom with another man. She didn't say anything to them. Just closed the door and went to her brother's room. He was 14 at the time. She told him what she saw. He went downstairs and verified it himself. Then they both sat in his room until I got home from work. The second I walked through the door, they pulled me aside. My daughter was shaking. My son kept clenching his fists. They told me everything. I went upstairs and confirmed it. She didn't even try to deny it. Crying and saying it didn't mean anything. I filed for divorce. During the custody hearing, both kids told the judge they wanted to stay with me. The court gave me primary custody. She got $1,000 per month. She moved in with him two weeks after the divorce finalized. For the next six years, all our communication was strictly business. Coordinate pickup times, split school expenses. Nothing personal. About a month after she moved out, she called me angry. Said the kids were giving her hell during her custody week, refusing to talk to her. Staying in their rooms, making things difficult. She demanded to talk to them. I sat them both down that night and asked if it was true. They both admitted they didn't want to stay at her place. Didn't want to be around him. I explained that it would be easier for everyone if they just stayed civil until they turned 18. That way we wouldn't have to go to court and make things messy. I told them I wasn't asking them to forgive her, just to keep the peace. They both agreed. After that conversation, I never got another complaint from her. I assumed they'd worked it out and that they were being polite during custody visits and just counting down until they could choose for themselves. My son turned 18 two years ago. He moved back in with me full-time and started college. He'd still drop by her place occasionally to see his sister during her custody weeks. He graduated last spring and got engaged to his girlfriend of three years. My daughter turned 18 last summer. She moved back in with me immediately.