Help crazy mother inlaw!!!?

I need help maybe i'm the crazy on idk but my mother inlaw is driving me nuts she wasn't so bad at first me and my husband have been together for 5 years married for 4 we are currently pregnant with our second child and just found out like 2 weeks ago what we are having which is a boy well my mother inlaw has been driving me crazy ever since we told her. She didn't act like this when i was pregnant with my daughter. She is trying to take my spot and do all the things that I would like to do like fix up all the baby stuff and I would also like to pick out some of my baby things i want to get not just what she wants. She even wants to come stay with us the week after the baby is born which is crazy because my daughter is two and in those two years of her granddaughters life she seen her maybe 5 times. But what makes me the most upset is for some reason she has recently turned really rude to me ever thing i say she screams at me even if i'm just trying to have a conversation with her i have never had this problem before but now i feel like she is trying to control me for some reason. my husband tells me to just tell her off but i don't know if he's really serious i don't want to get him mad at me but him and his mom have never really been close. I don't know what to do. And i'm Super confused about her change in attitude towards me after 5 years. has anyone ever been through this before? I just don't know how i am going to stay a week with her if she keeps treating me like this and i also don't want to be disrespected in front of my friends and other family members either.