My step son hates the baby

My husband had 3 kids when we met from a previous relationship. He and his ex stopped being a couple after their oldest son was about 4...the girls were oopsies because they kept trying to get back together. She was unstable and ended up in the psychiatric ward so my husband stopped trying to make it work (and she cheated on him multiple times) but that’s a whole other story. She’s fine now and in a happy relationship.

Well I’m 10 weeks pregnant and super excited, it’s my first. We told the kids this past weekend and the girls were ecstatic! I have a great relationship with all 3 of them since I entered their lives at such a young age. But the oldest who’s 10 was extremely rude and started punching a pillow and saying he didn’t want it and how he wasn’t happy. My husband spoke to him and he confessed he was extremely jealous. I talked to him too and told him I understood why he was upset but how he shouldn’t because we love all of them the same and how this baby was going to look up to him. He was a bit better but I could still sense the jealousy. We have told him several times that he can move in with us whenever he wants and my husband can’t stress it enough. He doesn’t want his son to come back later and say that he was excluded because he didn’t live with us when in fact he was always offered to move in. Has anyone else gone through this? Did the step child get over it? I feel bad but at the same time, it’s not my fault it didn’t work out between his parents and I shouldn’t have to feel bad about having a baby with my husband who is a great dad to those kids. We have great jobs and a home where they have their own room. They have everything they need including an enormous amount of love from all sides of the families. I don’t think I’m doing anything wrong by being happy and wanting my own kids with my husband.