I'm not going to answer my exes email that they've sent me.
Do you have a good reason for not wanting to answer the email?
I don't like him anymore and my life is better without him.
I realize that you might be upset with your ex, but its very rude to ignore the messages someone is sending you, even if it is your ex. You should send him a reply, even if it just says that you don't want to speak to him anymore. If you don't do that, he will keep trying to contact you and you will never be at peace.
I'm not doing it because I hate him
It doesn't matter if you hate them, it could be something important and you shouldn't shirk your responsibilities or duties because of feelings. Worst case, if it isn't anything important, then you can ignore it.