Dear Amy: I have been divorced for 10 years, after my ex-wife had an affair. She married the man she had the affair with. My ex and I share joint custody of our two daughters, ages 17 and 11. My ex and I have only communicated via text messaging for the last five years, and it is infrequent and only about the children. Recently I found out through my children that their mother is getting divorced from her current husband. My youngest came downstairs crying and displayed a text from her mother’s soon-to-be-ex, which didn’t only throw mom under the bus, but completely napalmed her. He told the children and her own mother (their grandmother) via text message that she has been having an affair with a co-worker and that she has done it before (with him).