Guilt feeling

I never thought I’d feel it but I’ve heard of people feeling some sense of guilt about their first not being their “only” anymore. I think because my son is 5 and so used to things being a certain way with our trio, I anticipate the transition is going to be at least somewhat emotional and difficult for him & I can tell he was feeling some sort of way (although very excited too) about having a younger sibling when we first shared the news with him. A lot of my feelings and anxieties are definitely exacerbated by the pregnancy hormones: How do you deal with the guilty feelings and what helps you ease your mind about the transition?