A bit scared to share with you all my gender disappointment

So I know I am a very ungrateful person for saying this. This is my first baby and rainbow baby and I just did the sneek peek at around 12 plus weeks. I found out it is girl. Now I know most of you will think it's fifty fifty and I know all that and I am a horrible person for thinking this but I always saw myself as a boy mom. My husband always wanted a boy and he used to tell me how will teach his son to play video games and stuff. It breaks my heart to see that his dreams are shattered. Even tho I always wanted one girl I never wanted my oldest child to be a girl. It doesn't seem right typing this but I can't discuss it with anyone. My hubby seems happy with the result but this evening he seemed down and I asked what's wrong he told me how much he wanted a boy but he'll be happy anyways. Even tho he says that I know deep down he wants a son. I just can't get over it but I feel bad for my sweet baby girl because I am being ungrateful.