How to tell my SIL?

So we’re on baby #2. For My family we announced with a “letter to Santa” from our first born which we gave to my parents, my siblings we invited everyone over for donuts and did a little announcement for the nieces and nephews.

My in laws are tricky because we’ve cut my mil and fil off because of drugs and other issues - we just don’t want them around us or our kids. My husbands sister doesn’t agree with us not having contact so she doesn’t come around much, she’s also always with my MIL so seeing just her is nearly impossible - every time we try to just pop by she’s either out shopping or my MIL is at her house. So she announced she’s pregnant by texting my husband on his birthday “hey I’m pregnant. Oh and happy birthday I guess.” (It’s her third) It was super weird. She doesn’t really seem to like her children - I don’t know, just a vibe I get from interactions over the years. So I text her a day or so after and said congratulations and asked if she was excited and when she was due and she was just like “No. April.” So I just let the conversation die.

Anyways - we are expecting also in July and I feel like we need to tell her but at the same time I don’t know if she even will care? My husband doesn’t seem to care one way or another but I also don’t want to burn any bridges he may not want burned because he was thinking like a man and not thinking about how his sister might feel…

I’m sure I’m overthinking this.