I am so sorry. Try to keep your perspective. Try not to engage him and if he engages you just ignore it. The anxiety is usually worse than the reality. My daughters therapist always tells her "it's almost never as bad as you think its is or will be". Hopefully, fingers crossed he will be on his best behavior since you are in public. Just stay away as much as possible and focus on your DD. It is her day and she deserves a special one!