You don't ever have to get married. You can both care deeply for one another and just be engaged, that way you won't be tied to one another's crazy family problems, and if things go south you can still leave without so many complications. If you want a ceremony to celebrate your love for one another, you can have that, but you don't have to be legally married.
I'm saying this because I want you both to be happy without you having to be legally bound, in any way, to the crazy, horrible garbage fire that is very clearly his family. You wouldn't just be binding yourself either, you'd be binding your children. You'd be giving your children a racists set of grandparents and great grandparents. Connecting them to a whole family that judges and hates them based on skin color, and who, if something happened to you both, would have potential legal rights to your children, if they wanted to go to court about it.