NEVER leave your baby alone or unwatched where your older child can reach her. Your baby's room should be not only babyproof, but childproof as well, preventing your older child from going into the room without adult supervision.
You can't force your older child to love (or even like) your baby, so don't even try. Because your child will feel jealous and resent the baby much of the time, it will be difficult for him to have many (if any) warm feelings toward the baby. Try to understand this and acknowledge your child's right to see the baby as a royal pain. But at the same time, suggest that some day (hopefully) your child and your baby may get along well enough to play with each other and, who knows, maybe even like each other.
If the baby already likes him, your child will find it much easier to like the baby. So try to help your child feel that the baby likes him. By the third month, it should be relatively easy for your child to get the baby to smile at him. Make a point of noticing and milk it for all it's worth.
No matter what he feels, give your child free rein to express his emotions, especially those regarding the baby. Try to avoid making him feel guilty about hating the baby. In fact, if he's three or older, your child may feel an excessive amount of guilt about hating the baby all on his own. So give him permission to say it out loud for all to hear, and let him know that you understand his feelings and that he need not feel guilty. (Of course, you also might want to add that you hope those feelings will change as the two of them get to know each other better.) Your child has a right to his feelings and they should not be regarded as shameful. After all, they are perfectly normal and understandable. (Just think how you would feel if your partner brought a new spouse home.)
Of course, just because your child has leave to express his emotions in words doesn't mean you should allow him to act them out. Make it clear from the start that though you welcome his verbal expressions of feelings, your child is not allowed to harm the baby in any way. You can give him at least three good reasons:
- you won't like it and will certainly discipline him for it;
- your baby certainly won't like it and will cry, meaning you will need to pay even more attention to her; and
- your child won't like it, at least not for more than a moment. Even a toddler will feel guilty about hurting a baby
Try to do more than merely defusing tense situations that might cause your older child to strike out at the baby. Do your best to remove the opportunity for your child to hurt the baby. If possible, aim to prevent your child from inflicting even accidental harm on your baby. Toddlers and preschoolers still have a magical belief in wish-fulfillment. So even if your child hurts the baby by accident, he may feel a tremendous sense of guilt. After all, that may have been just what he was wishing for.