Fiancè's teenage son acting more clingy towards him

Me and my fiancè just had our daughter 5 weeks ago. My fiancè has a 14 almost 15 year old from a previous relationship. He is with us full time. My fiancè has had full custody the entire time I've known him because he was being abused by the mom and her boyfriend. I do feel bad for him because had the abuse gone in any longer he would have been another Gabriel Fernandez case but he is just so rude. Any time I've been nice to him he ignores me and he is so clingy around my fiancè and it's only gotten worse since we had our daughter. He was supposed to be gone last weekend over a friend's house. Thought we would get time alone with just us and the baby but his son called because he was having a panic attack and wanted to go home. When he got home he just sat on my fiancè lap. He's not 5. My husband babies him at times. I feel sad because I thought we would get time with just me him and our baby. I expressed my feelings and he got mad and said it's not just the 3 of us. I wasn't trying to say it was. I just wanted that time together. He said I know marrying him means his son comes with. I never said he didn't. Just really wanted that time. He said when his kids need him he's coming. I know his son comes with the package but does he need to baby him? He's a teenager! We have an actual baby who should be the only one being babied