I don’t want to tell his mum that I’m pregnant 😖

I’m only 6 weeks pregnant so I know I don’t need to worry too much about telling people for another 6 weeks but I don’t want to tell his mum at all. His mum and I have never really got on, it all seems faked and forced for the sake of my partner and our little girl. After I had my little girl ( by emergency c section) I fell pregnant just 3 months later. His mum got really angry that I was pregnant and pushed me towards having an abortion. It was the biggest mistake of my life. I’m pregnant again and I adore this baby and I know I will defend this one with everything I have! J won’t make the same mistake again. I don’t want to tell his mum I’m pregnant at all and I worry that when she does eventually know, if she’s nasty about it, that could be the break down of whatever kind of relationship we have and make it difficult for my partner. I don’t really like her and I’m tired of just letting her treat me badly. If she does get nasty am I being unreasonable if I tell her to leave me alone unless she can be nice about it? Or at least keep her opinions to herself?