Can I say no to celebrating my nephews birthday at my wdding?
Why do you want to say no to celebrating your nephew's birthday?
Everytime we go out with him, he starts to cry and there won't be any feeling in it.
Rightfully, your wedding day should be all about you and your partner. However, you can include a small frame of time during your wedding to acknowledge your nephew and his birthday. This will not take away from your special day and your nephew will be grateful to not feel ignored on his special day.
NO, I don't want him there when I get married.
He is a young kid, isn't he? You should give him a little bit of acknowledgment at your wedding, even if your wedding day should be all about you-- it doesn't hurt you to let him know that you care, even if you find him annoying, you have to remember how young he is. You were annoying at that age too, most likely.