significant other, babymomma, and Mother in law 🤦🏾‍♀️

He has a child from a previous relationship but the child does not live with the mom but lives with my SO and I. 

My SO's mom keeps in contact with her (I guess because that's her grandsons Mother) anyway the other day we were talking about the baby and she said something like "she's gonna be upset when she finds out you're pregnant" (she as in the babymomma) and in my head I'm like who the fuck cares!!!?? She has no choice but to accept it..but I felt kind of offended like 😒 who cares AND who's gonna tell her, you? 

And it makes me uncomfortable that my SO's mom comes to me and talks so much shit about this girl but yet that's her "friend"

...she's always on the phone with her..(my SO hates it due to the fact that this girl took him to court, had Acs called on his mom and accused all of them of being drug addicts and a whole bunch of shit YET he still has custody of his son So apparently he can't be all of these bad things 🙄 )so with all of these petty evil things this girl did in the past..his mom is still buddy buddy with her (which I don't care) but the question I have is ... and the point I'm trying to make is, I can't help but to think my SO's mom might be telling this girl things about our relationship ... or maybe I'm just jumping to conclusions? Maybe she's trying to keep a "cordial" relationship for the sake of her grandchild... what do you think? And how would you feel?