Bullying can cause real harm, even if the bullies never set a hand on your child. The psychological pain can be extreme and can lead your child to doing something everyone will regret.
In this situation it is particularly important that your child knows that you love him or her unconditionally. Sometimes they feel like the outsider everyone, and they just need someone who will love them no matter what.
Don't take it for granted that your child is doing OK. Tell them that you love them today so they know they have someone to trust and don't have to suffer by themselves.