need advice..

Ladies.. I feel like a pretty crappy sister in law, well, not even that. Me and my fiancée (24 & 23) surprised everyone earlier this month with us expecting our first child! His younger brother and EX girlfriend, get back together to announce they’re (18 & 17) also expecting. We’re exactly 4 days apart for due date! I was happy for them, but ever since that day it’s been about them. I went and bought a bouncer, and they came out of our shared living room after seeing it and WENT AND BOUGHT THEIR OWN. THE SAME DAY. I just feel like I can’t be happy because everything I try to do, they have to one up me with everything. If I have an ultrasound scheduled, she goes and gets a private one the same day. I’m beginning to really despise her and i’m trying my not too. Please help.