My step-mother and I are not very close at all. She and my father live in a different state. She recently emailed me a list of people she wants invited to my wedding. This list included her son & daughter. I was NOT invited to neither her son's or daughter's weddings (and my father & her have been married for 17 years). My fiance & I are paying for a majority of the wedding. My dad gave me $1000.
My dilema is this, I don't want to invite any of these people on this list, nor her children. What do I do?

I would just explain that the list is increasing and you did not want a wedding this large. Also explain how you feel and since you are paying for the majority of your wedding I would not think that it would be a problem. If she is still persistant maybe mention that you where not invited to her childrens wedding and do not feel obligated to invite them.