Guilty about having another baby?

I have an amazing baby boy who is 4 he was diagnosed with autism at the age of 2 and improved and they said he didn't have autism anymore it was just delayed learning ❤️ I'm pregnant with baby #2 and feeling guilty I love my son and I don't want him to feel as if I replaced him. Especially when I give birth I'm going to be exhausted all the time :( has anyone ever felt like this?