Our relationship experts have tons of useful and free advice on numerous topics to help both of you on your journey of growing together. I hear you say that you feel that the relationship is not worth saving, which may be true, but they have children together, so they are going to have a relationship with her for many years, whether romantic or not. Honestly, I sometimes struggle to find someone who feels like giving me unbiased relationship advice. When I got married almost three years ago, at the wedding reception I asked some of the older and wiser people who attended to give me some advice from their own relationships to make sure my wife and I didn't shit in (the same) bed.
He's gotten to the point where he asks me if I've been in a relationship before him and if I'll be in a relationship in the future. Just as causing pain to the muscles allows them to grow stronger again, introducing some pain into their relationship through vulnerability strengthens the relationship. But seriously, you sound like an intelligent and proactive person who cares a lot about this relationship AND because this relationship has a lot of strengths.