Not only is your anger not of a benefit to you and your DD's, it could be detrimental, which means you need to make more of an effort to address it.
The people in your life who keep relaying social media nuggets from OW are not your friends! Everytime they start, shut them down and tell them that every time they choose to 'update' you shit stir they are hurting you and if they do it again, you will prioritise your mental wellbeing by cutting their arses off.
You have been treated very badly and you have every right to be upset and angry by the behaviour of both your Ex and the OW but it doesn't define you or your DD's. Change the narrative in your head, the current move is an opportunity not a something terrible as a direct response of your Ex's shitty behaviour. I don't mean to be insincere but you need to stop being the victim of their shit, even when the shit is ongoing.
I can't stop my Ex from being the shit that just keeps on giving but I am in control over how I respond and best way I can support DD, is by being available to help her to work through her feelings without her worrying about my feelings. Remember when they were little and they'd hurt themselves and they would immediately look to you to validate their response, if you were panicked, they would most likely panic and howl but if you were sympathetic and reassuring that they could cope, more often then not, they would. Well it's the same now.
Anger has its usefulness for galvanising us into action but its usefulness has a short shell life and it will become corrosive if you choose to hang on to it to long.