I totally understand what you are going through. my husband was up to all sorts when my baby had just turned 1. recently (she’s now 4) she’s been crying screaming at the door when he leaves her back , and screaming she misses him. this is all completely new and goes on for about 15 mins. I just hold her ( if she’ll let me) and sit near her til it passes but it’s very hard. hopefully in time it will get easier for her but my heart breaks to see her like that . worse still the ex is expecting a new baby eith his new fiance, I’m dreading what this will do to her.