I think that if the bride-to-be is a nice woman, OP, that you should go to the wedding - but, if you do, just because you're there, doesn't mean that you're obliged to spend any time with these... I hesitate to call them friends, because they're so blatantly not. They're "friends", perhaps, but not friends. I'm sure there will be other guests whom you can socialise with during the reception...?
As previous posters have said, they do seem to be very jealous of you. That's why they're so nasty towards you, I suspect - they know, deep down, that they've not achieved much in life other than marriage. Which is fair enough, if that's what they truly want out of life, but their jabs at you suggest that they're hankering after the career and the freedom which you, as a young, undoubtedly gorgeous, single woman have. You're not shackled, like they are. Subconsciously they're trying to make themselves feel better about their lives, by hurting/bringing you down with these nasty jabs about your life. They seem very immature, very insecure, and... well; I don't know them, but I feel very sorry for them!
25 is extremely young to be married, and dealing with all the responsibilities that brings. Out of my group of school friends, 4 were married by the time we were 25/26. 4 weddings. 4 sets of dreams of happily ever afters... Within five years, 3 out of the 4 were divorced. One is on her second marriage, one refuses to ever get married again, and the third is currently shagging his way around the female divorcees of North Wales... 
Concentrate on your career, being young, and finding people who truly appreciate you for who you are - not the rings you wear on your finger! Because you do deserve better than these "friends" are willing to give you right now.