Weddingbee boards

*EDIT* i just realized i posted this to the wrong forum and i don't know how to move it, sorry guys!! **

I'm newly engaged and won't be getting married for another 2 years, but already am feeling family stress on all ends. We are planning our own engagement party. I know it's not necessary to have one, but we would like one and so would our families. Anyway, I am having a very stressful time dealing with my dad. Here's the story.

Mom left dad 11 years ago and dad is still VERY bitter over it (kind of in a very immature way). They definitely can not sit near each other. I'm going to seat mom's family on one side of the dance floor and dad's family with fi's family on the other side of the dance floor. Now, here's the issue. Dad is complaining to me that he wants his table to be closest to mine (me and fi are going to sit with our closest friends at the head of the dance floor, opposite the DJ). I tried to explain to him that traditionally bride-to-be's family is on one side and groom-to-be's on the other, and since mom's family is so big and dad doesn't want to sit near any of them, this is really the only option I see. I asked dad if he could think of a better idea. Very immaturely, dad told me maybe I should seat my mother, her new husband and his kids in the parking lot. I just don't know how to deal with him being like that. I've told him numerous times it hurts me, and I've also tried telling him how stressed I am. He replies by telling me "I know you're stressed, but you'll do the right thing." with a tone in his voice that implies 'you'll do the right thing, which is what *I* want you to do.' I thought of seating dad at the table WITH fi's parents, but there are too many people to fit at one table. And mom's side of the family is too large to move over to the other side with fi's family. Dad doesn't want to be near ANY of mom's family (not aunts, uncles, cousins - nothing). I'm about to tell dad if he wants me to have an engagement party he should throw a small one just for his family if he's going to be this difficult, but then I wonder what the hell I'm going to do for the wedding.

Thanks guys. I know I'm going to have to be harsh, but I'm normally a VERY non-confrontational person. I'm so scared of saying something hurtful to the people I love, I usually let things slide a lot. I know this is something I can not avoid and I'm going to just have to tell him to grow up, and that if he doesn't like the seating arrangement and can't come up with something better he'll just have to deal with it or not come.