Ex's pregnancy.

My husband and I have been separated since March 2024. Not to get too much into it, but it was very toxic. We were together for 12 years. We started dating when I was 15 and he was 18. He cheated on me a lot and there was a lot of verbal and mental abuse. He was very controlling and manipulative. I had finally had enough and found the strength to walk away. We have three kids together a ten year old, six year old, and three year old. About two weeks ago, he told me he had a special friend that he wanted me to meet. I want to keep this as short as possible but a few days ago he told me that she is pregnant. He mentioned that they had been dating for 4 months. There's so much more to this but I want to keep this as short as I can. I've been going to therapy for 1.5 years now. I've talked to my therapist about the confusing feelings and fears I was having. My ex and I had discussed waiting at least a year before introducing a partner to our children. Given that he doesn't know her very well i'm very hesitant on introducing her to our children. He's planning to move in with her soon and I discussed this with my therapist and my fears about my children being around a stranger. My therapist told me that if I am uncomfortable with her meeting them. I should let my ex know. I did mention something like this to him and he had told me that my daughters are strong and that they'll get over it (they're children. They shouldn't have to be strong.). The woman he's dating is 22 and she also has three other kids ages 1, 2 and 3. So not only would he'd be introducing a new woman and a baby. He would also be introducing three "step siblings." My therapist had said that this could be traumatizing. My daughters are still processing the separation. He had also told me that because she is very young. She needs help taking care of her kids and that he would be helping her. She is 10 years younger than him. My therapist told me that I could tell him I don't feel comfortable. About my daughter's meeting her or knowing about the pregnancy. At least for right now. I don't know if this makes sense because of the situation but I am genuinely afraid of my kids being around strangers especially spending the night in a home with a stranger. His judge of character is terrible. I know this is long but overall, this is his life and choices but I want to make sure my girls are safe in every aspect of their lives.