I need help defeating Vorpar because apparently, I picked the extremely hard route to go. Does anyone know how to defeat him with sylvorpa? Or is it currently impossible?

It doesn't matter what kind of pets you use, it matters your pets' builds and knowing Vorpar's strategies. ^^

Creating A Battle Party 101
Guide to Pet Speccing and Gearing!

Those two guides should help you make your party more focused on taking hits and dealing damage.
In particular, your pets seem to be on the right track, but you might want to take a better look at the equipment on your pets to get them more uniform. (ie Viola seems to be a magic damage-dealing tank, so she should have all Illusionist gear; I can't tell what your pets are tree-wise or role-wise to tell you for sure what your pets need, because the gear you give them greatly affects their stats)

If you need any help, tell me what roles your pets are according to the guides (ie tank or damage dealer, and either magic or physical damage in either of those), along with what proficiency trees you're using for each of them.

Tips on Defeating Vorpar

Skimming through this thread should give you tips on how Vorpar works. Knowing his mechanics throughout the battle will help you.

Thanks a bunch! That's a huge help ^^