Separated and X has convinced children I was problem

25 years together, most of them very good but my partner cheated on me when things got tough financially and emotionally. She called me horrible names, said she had never loved me, told me I wasn't any fun and too boring, told me to sleep with someone else othe than her, it goes on and on. I suspected she was sleeping with a work collegue and she denied it. She had friended him on FB and was recieving messages from him at all hours. She came home from work very late, wouldn't answer her phone or left it at home when she went out on weekends. We broke up and weeks later, I text her about my observations and that I had someone who had caught her out at work tell me about things not being right. She confessed that he had offered for her to live with him, she confessed that she had intended to leave the family home and live with this guy, she confessed to having told my sister about having made all the preperations and having somewhere to go to leave me.

Now my kids are convinced I was the problem, they will not speak to me at all, the guy from the messages is NOW my X's companion and features in FB posts with my family. My old work collegues have seen my X out with the guy. But my X has convinced the kids it all only happened since I left. I have texts from my X confessing to it all and admitting it happened before we broke up- If I show my kids it would make them believe- but would it improve anything? It is horrible to be considered a liar and the family breaker, when I was 100% faithfull and left because my partner had had an affair.