Should I share with sis in-law

My husband and I are separated. I posted my story about a wk ago. And due to the situation many ladies advised not to update him on my pregnancy updates. Reason is he had an emotional affair, ended it but is still in contact with the other woman, I get stressed thinking about it and I don’t want to share my appointments because he has a big mouth and will probably tell her.

Anyway his sister is very kind and has told me if I need anything to let her know and keep her updated. This is my first baby and I’m wondering if an ultra sound pic is one of those things to maybe send her ?