Stepmom and FTM -- hormones triggering my green monster

Any other stepmom out there expecting their first baby with their spouse? I have three stepkids and am pregnant with an "ours baby" as I've heard people say. I'm sure it's hormones, but I'm experiencing lots of anger and emotions I wasn't expecting. Anger that my husband has already been through this before with someone else (which obviously isn't news to me but bothering me more than usual)... A feeling of wanting more alone time with my husband... Like my inner cave woman has been ignited and I'm wanting to protect time and resources before my baby comes. I feel so guilty for having these feelings bc my stepkids are really great kids, and we get along great. They are so excited for their new baby brother... And I'm just wanting them to go away. Please tell me someone else can relate!