I found out something that made me feel like shit

So tonight I was at a party with my friends and we had a conversation about my ex and all the abuse I went through with him. For some of them, it was the first time hearing everything I went through. It got quite emotional, during the conversation it was brought up how he has been posting photos of his new girlfriend and my daughter on his social media, it really hit a nerve and even though I know its something I have to get used to, it hurt. My friends didn't tell me to hurt me, they were shocked that he's let our daughter meet her considering they've been together for 3 months and we've only been split up for 4 months. How should I feel about this? Is it normal that I feel as sad as I do, even though he abused me throughout our 7 year relationship? I know I can't stop his girlfriend seeing my daughter on the weekends he has her but I also can't help but think she's taking my place and he's instigating it.