I'm not going to invite my step-mother's siblings/relatives to my wedding ceremony even though they're invited to the reception
A lot of people do that! What is your reasoning though?
They make me feel repulsed. They also claim that I haven't reciprocated my love to them.
A wedding is an intimate affair. It is okay to only invite who makes you feel comfortable to the most important day of your life.
I know that is why I don't want to invite them to neither party.
Although some will be upset, it is your wedding and you should only have the people you love there to support you. It will sour it if you get people you don't want there.