Feeling worried about announcement-long explanation

I'm 35, almost 36, with 4 kids ranging from 19-8. My husband and I thought we were done after our last one, but decided late last year that we would try again. One month later, I get my BFP.

But now I'm almost scared to tell my family, and my older kids. We are waiting until after the first ultrasound at the end of the month regardless.

Why am I scared? Because I feel like no one but my middle child will be excited.

It's not so much my age, most of my friends either had kids really early (like me) or around 30/32.

I'm going to be very open atm and explain... My oldest is my stepdaughter since 2yo. We were very close up until a year ago. Her mom has been struggling with infertility and I think she'll see it as a slap. I pray for her mom all the time and am very sadden with her trials in trying to have another. So, I'm not heatless, I do understand.

My littlest one just likes being the baby haha she'll be okay.

But my parents...one set is dealing with health issues, the other are basically raising my sister's child and I've noticed the change toward my children.

Has anyone else had these fears? How do you deal with it????