Family BBQ with sister in law

So I was over at my husband’s dad’s which we just moved to. We were celebrating his dad’s 62nd birthday and he wanted a bbq with his sons and wives that live in the state. Well my husband’s brother’s wife is very socially awkward and one to not really acknowledge people unless talked to or just taking to her husband. But she has this quirk where she always feels inclined to state her opinions on things and if you disagree she will start to argue unless you say something right and she is in the wrong . Then she just goes silent and gives that person silent treatment for rest of that time. She definitely is comfortable with this side of the family since she states her opinions and she’s been in the family 2 1/2 years before I got married to my husband. Well we found out we were pregnant and got a congratulations from all the siblings and their spouses but the sister in law. I just ignored it knowing we aren’t the biggest fans of each other. Well while we were at the bbq my MIL brought out tiramisu(rum free) as the cake to sing happy birthday. She dished it up and I asked if the coffee that was in it was caffeinated or not due to me being in the first trimester. Then my sister in law said “well there is caffeine in everything.” I responded by saying “yea, but if you have to much it can cause deformities” but she cut me off before finishing this sentence and asked “if I wouldn’t eat chocolate because that has caffeine.” I said “not really since I’m not a big fan of it. But it doesn’t matter anyways because coffee has stronger amounts of caffeine in it anyways.” She went silent and started ignoring me after I said that. But I just bugged me because she has never been pregnant, doesn’t really like babies, also keeps pushing off ttc even though she’s told her husband she will start since he wants one then she backs out. But it’s just frustrating to me because why should she even think she has a say when she doesn’t even want a kid. I told my husband if she makes another comment on what I choose to do with carrying my baby. That she can shut her mouth and make her own decisions when she’s pregnant. Sorry if this offends anyone but it’s just frustrating to me when people try to tell me what to do when I’m not asking their opinion or for their advice. It might also be my pregnancy hormones but... We’ve had many issues before this. We resolved them but she’s just doing the same crap and I’m over it 🙄