Are you and your partner planning the wedding yourselves or do you have parents involved? The reason I'm asking that is that if it is just you and your partner, you have the right to exclude anyone from the guest list and you need not offer any explanation. A simple, "I've had to distance myself from him for a while" could be all you need to say.

If you are planning with your parents, I'm going to assume that they know of the abuse. Being the mother of a teen who has suffered sexual abuse, I wouldn't think twice about excluding that person from her wedding. If your parents do not know of the abuse, maybe it is time you tell them. I, myself, was raped my freshman year of college and only my parents and one aunt knew about it. After I learned of my daughter's trauma, I told all of my family what had happened to me and I felt so relieved not to have to hide that "dirty little secret" anymore.

Good luck to you in your life together.