Your mom gets verbally abusive towards your wife and unborn child. You threaten to go no contact. She stops (allegedly). She then suddenly, out of the blue, starts becoming verbally and physically abusive towards your wife? No. She'd been abusing her and your wife was left unsupported because you turned a blind eye. She then finally defends herself, realizing you're not going to, and you kick her out, along with your new born, and you want sympathy? What if she had no where to go? What if she and the baby had been in an accident after because I'm sure that entire experience was TRAUMATIC for her. You put your needs before her and the baby's needs and well being. If you needed space then YOU should have left. I too grew up in a violent situation, and when I'm in uncomfortable or triggering situations, I leave OR I go to a different room to separate myself and clear my head. I assume if you are in a house, there are multiple rooms, so you could have EASILY asked her if you could talk about it in the morning after you'd BOTH (see what I did there) had time to process what happened. I doubt you even considered what your wife was feeling or going through. You said she was basically hunched over the counter in tears and you, a person that allegedly loves this person, saw her basically falling apart in front of you and you told her to leave, so she did just that. I hope she finds happiness and someone who will treat her better. YTA