If all the stitching was going to rip you shouldn't have even been able to get the dress on.

You should be able to return it. Most online companies have a decent return policy.

You could still be a size 8. Every company's sizing runs differently

You should always measure yourself before buying something online... and obviously you were putting way too much pressure on the material if it didn't rip only once, but twice. YDI.

First, measure the dress and check it against the measurements online. If you went by the sizing guide from the website and the dress you got doesn't match it, contact customer service, you can almost certainly get a refund/exchange in that case. (and if you didn't go by the sizing guide and just figured "eh, I'm usually a size 8," sorry but YDI a bit, you should always check measurements when you buy online). If you can't return the dress, you could look into getting it tailored. I'm assuming it's a pretty nice dress if you had to save up for it, so maybe it's worth salvaging. Tailoring can be expensive, but for pricey clothes it's still cheaper than buying a new dress (depending on the cut and what type of holes we're talking about and how much bigger it actually has to be made). If nothing else, you might be able to repair the ripped seams and have a really pretty dress to give to a smaller-sized friend. Also, I hope you have a great time at the party no matter what you wear :)

I really hate when people write in present tense when talking about something that happened in the past.

You need to make sure you order "American 8," which is standard size 14 relabeled to make fat people feel better about themselves.

When the Gender shows a male silhouette, and it makes this a little different. (didn't say bad, or weird, or anything negative, but different than expected.)