Worried for my forst born

So i am pregnant with my second child. My son who is now two doesnt belong to my husband as he came from a past relationship. My father in law made a comment the other day "finally a blood related grandchild" im so paranoid that when our new baby gets here my son will be treated differently...mind you im so hormonal i cant even deal with myself which doesnt help! I just feel at a loss...my husband thinks he was just thinking out loud and ment nothing by it but should i keep a stronger eye on it?