This is a post no one wants to write, but that definitely needs to be written.Most of us really do wish our weddings could be sweet celebrations of love and family, commitment and community. This is going to be hard, so you need to be completely solid in your decision.Simply state that the person will not be receiving an invitation, and then respectfully decline to answer further questions.
Don't put it off, and don't use platitudes.
We're just going to assume that you feel you've got a really, truly legitimate reason. This is about you feeling like you're making the best decision you can for yourself and your wedding.
It's not our place to judge the legitimacy, and ultimately it doesn't matter: if you feel it strongly, then that's your decision to make. As always, you can't control other people or their behavior.
You likely do not ever need to contact someone to tell them they're not invited to your wedding, but if they or another family member ask you about an invitation, we suggest you use straight-forward, un-charged language.
Here are a few examples: Do not cave to emotional blackmail, do not cave and fight with people over this — this is your choice and you have to stand firmly by it. My policy is to discuss my decision once with a person — and then no more.