Should scrotes be in contact with baby mamas?

Obviously if there's kids involved the contact should be limited to talk about those. But since my ex cheated with the baby mama, any sort of positive contact with her outside of texts about apointment feels like a red flag. This scrote I know told me he and ex go to amusement parks with the kids, so they know that mommy and daddy don't hate each other. Liiiikeee you're giving them hope they'll fall in love again like the Parent Trap? Sickening. Poor kids.

Am I crazy that I feel this crosses a line?