Nervous...

This is my third baby (daughter 12, son 6) and I've all of a sudden started to feel very very nervous that I won't be able to cope! My husband works away on a rotational basis so there will be weeks where I will have no one to help! I'm worried I start to take it out on my other children, especially the older one. My kids are really well behaved and don't deserve to put up with any of my mood swings! This pregnancy was unplanned and if I'm completely honest I have never really completely been able to invisage another person in our family. I feel like I may be falling into some sort of anxiety or depression!