Sad.. Please help

I have a 4 year old son and I'm almost 13 weeks pregnant with my second baby. The second was planned and was decided for a sibling for my son but he hates babies and won't talk about it and doesn't want a baby brother or sister. It tears me apart to be so happy about the baby when I've angered my son and idk how to make him ok with this new baby. Any ideas would be greatly appreciated 😔