Need Help!!!?

My parents are divorced and have been since i was 3. My dad is remarried but my mom is not. And growing up my mother was never around. She never came to see me on bdays or anything. Didnt even go to my graduation. and my dad and stepmom hate her for that and she hates them. but my question is this. What do i do about inviting all 3 of them to my wedding? Im afraid that there will be a big fight. I mean my dad didnt even go to my half sisters wedding cuz he was afraid my mom would be there. Me and my half sis have diff dads.But what should i do about all 3 of them being there? Im worried about it.