An old friend of mine (from high school) invited us to her son's birthday party, next week and I'm torn on whether we should go or not.

They're FAR from veg - there'll be cake and ice cream full of animal products.  Probably only hot dogs and hamburgers for food.  (We went last year and sure enough, even though I told her we were veg there were NO veg options for us to eat) Lots of crap candy.  I'm sure you all can imagine.

Also, the kid is kind of a brat.  He watches violent cartoons all day long, is spoiled relentlessly by his grandparents (the kid has every stupid toy fisher price ever made) and eats all sorts of crap food, including only those capri sun drinks (which'll be the only drink for the kids available) with high fructose corn syrup and chemical perservatives.  He's also vaccinated (which my kids aren't) and attends a day care a few days a week.  He's not the sort I want my kids getting ideas from, you know?

We went to a birthday party a few months ago for my sister's friend's kid and it was also a disastrous.  No veg options, disgusting cake and ice cream, only soda and capri sun to drink.  A few days after the party, both my girls came down with bad colds (and they've been sick only maybe a couple times each in their short lives) and then, so did I.  So, you can guess how enthusiastic I am about going to another one.

I'm not trying to be one of those veg moms who never lets my kids do anything "normal" but I feel like I'm compromising my principles by taking them and just letting them eat and act however.  I don't want to show them that behavior is acceptable, but I also want them to be kids and have fun!

Where's the fine line?  How do you guys judge what's right and what's fun?

I think it is important as a parent (not just a Vegan one, either) that we set a good example in every area possible.

I don't know if it was meant to be, but seeing how one can't hear the tone in text, it seemed like you were almost snobbish while telling this story.
I'm sure I will step on someones toes, but so be it.

Being Vegan doesn't make you a better person, a smarter person, a god etc. You are simply another form of the guy next door.
We could easily say we're more aware and compassionate for all living beings, how do measure that? I have no idea.
I know Omni's that put in more hours volunteering with animals then I do, I know Omni's who run the soup kitchen that I've never been to etc.
Keep in mind that we're all humans, we all have the same needs, wants and goals, to be happy, fulfilled and at peace.
Some just go about it differently since happiness and peace is different from person to person.

I don't know how the host of the party is as a person, but I think it goes without saying that she can't be that wicked and mean or she wouldn't of invited you and your little one, right?
I also feel sort of bad reading the story, bad for that mother and her child, I would never want someone around me, vegan or not, that talks that poorly of me and worst yet, my child.

You're little one is invited to the party, keep that in mind, the parents obviously think they are friends, surely if he said "I hate that kid" they wouldn't invite yours, yes?
So let your little one be a kid, they have plenty of time to grow up and be judgmental and rude, let them just breathe easy and have fun regardless if the guy next to her eats animals or not.

He is a child, he only knows what his parents have taught him, and they only know what theirs taught them and what they've been willing to learn as adults, I can say that the sure fire way of turning someone off of Vegans and their kids is to act holier then thou.

Any way, this is a long rant because it was needed, to read "A friend from HS" and "the kids a brat" from an adult is shocking, I hope that your own little one is never called a brat, and also never grows up to judge anyone in such a way.

In closing, you're the only Vegans there, you can not expect a mother trying to plan a party for her child and doing all of that work to  remember to research and plan what to do for the two vegans, that's your job!
It's your chance to set a good example, bring a yummy dish you can eat as a main, bring a sweet, turn them onto the tastes of good Vegan food, not turn them off with being abscent because of food issues and/or rude.

Just remember, we all started some where, we all knew a Vegan a Vegetarian an activist etc, none of us would be here if they put such a sour taste in our mouths back then would we?

Good luck to you and your little one at the party.