AIO- Mom withheld a family pregnancy from me and refuses to apologize even though it looks like she doesn’t trust me.

For context, this cousin that had a baby is a pred*tor that sexually harassed me since he was a teenager (I’m older by 6 years) and even catfished me into sending lascivious pictures when I was working as a livestream. I am not his only victim (his new wife has also given him a playground of potential victims being a teenage sports coach) and no matter how many times I’ve spoken up about him in the family it has essentially been swept under the rug and if anything he just keeps being rewarded for his bad behavior with their enabling.

For almost 3 months my mom knew about that his wife was pregnant and didn’t tell me because she thought I would have a meltdown since I said that I would if this happened but I said that in jest and she took it literally. My mental health has been weaponized against me my whole life so this isn’t anything new but of course I was furious and started crying when she told me the baby was born. This is extra sensitive to me because I’m 35 and fighting to have a baby of my own, going through extensive testing and weight loss (almost 55 pounds down) over the past couple of years.

I told her she f**ked up by not telling me sooner and she said she did the right thing. IMHO it just proves that she didn’t trust me and I keep telling her she needs to apologize and take accountability. She keeps telling me I’m 5. I told her to my credit I could have reacted A LOT worse.

So am I overreacting?