My ex girlfriend has been sending me death threats because I am getting married?
Psycho. Print out everything she's been sending you and turn it into the police. Seriously don't sit on stuff like that. You really don't want to take a chance that it's just a bunch of wording and she wouldn't act on it. It's better to be safe than sorry. My brothers (now wife) has had the same issue with an ex of hers. Had to get a restraining order + a no-contact order. You should consider doing the same. You don't need this in your life, turn it into the police and do what you need to do to keep both you and your fiance safe because if she's nuts enough to go after you, you just never know if she'll end up expanding that idea. Take no chances!!
Block her file a restraining order