Help please!!!!!!

So I just found out Monday I'm pregnant for my 3rd baby. But since I've told my other 2 kids that are 12 and almost 11 have been awful!!!! Fighting like crazy. Making me get to the point I have to yell at them. It's stressing me out to the point of tears. It scares me I'm going to lose this baby because they are making me get so upset with them. 😧😢 I just don't know what to do anymore. My husband isn't much help because they aren't like that when he's home only me.