I'm engaged to be married for the 2nd time. My fiance hates his family. I have kids. What should we do?

We agree that neither of us sees the point in wasting precious finances on a big expensive wedding. His family are dreadful to me and our relationship (as I am several years older and already have children) has brought out the worst in them and he has made the choice to sever ties. I tried for some time to get along with them but then they started a hate campaign about me over Facebook! LOL! I'm serious :( Suffice to say, the family has issues. To save the drama (and the money) I'm happy to elope but I am concerned about how this will effect my kids. My fiance will do whatever I want. I am not close to my family, but they did attend our large engagement party, which was to take the place of a big wedding. His family attended also but they haven't spoken to him since and made no effort to be involved on the night. His twin got married and completely overlooked us at his wedding. We got the courtesy invite and my fiance was invited to the bachelor party but then completely ignored. His twin also gave him the ultimate slap in the face and asked my fiance's worst enemy to be the best man. I didn't get an invite to the hen's night. It was discussed several times in front of me and some effort made to exclude me from the entire thing. I can't even discuss my children amongst them as they're not biologically my fiance's. I brought the kids to meet them and they gave my teenagers a pack of textas and a colouring book and proceeded to ignore them. My kids did not attend the engagement party. My daughter wants to be a flower girl when we get married. I don't know what to do! I guess I'm after others' opinions of what THEY would do. I already know what I could do. I just need to feel justified in doing it. My first marriage was horrific and I've spent a decade getting over it. I don't want any stress or rubbish in this one lol. This is a big Jerry Springer situation and its funny if you look at it from an outsider's perspective - which sadly I can't do. I just want to skip off into the future with my wonderful man and leave the crap behind!