Scared he might leave

My so hates that I had sex with another guy before I met him because I was my so's first and he doesn't trust me because of my past I've never cheated or anything but he says when he thinks of my past he's disgusted with me and with himself we both love each other very much I'm just scared he's not going to be able to keep accepting my past I love him and don't wanna live without him he is the one I need advice I don't wanna lose him he's everything to me