If it makes you feel any better, quite a few of those relationships that were "solidified" when those people were in their 20's are going to unravel pretty soon. Look at the odds. It's extremely unlikely that all of those relationships are going to succeed. The fact that your paired-up girlfriends are telling you that you shouldn't feel lonely or concerned is indicative to me of how clueless and insensitive they are. Maybe they'll have some realizations about this when they come crying to you about their own problems.
You're actually at an advantage, believe it or not. You are who you are. You're not some larva trying to push butterfly wings out too early. You have a LOT more to offer to the right person than most of the other singles out there.
Pep talk aside, it's perfectly understandable to be heartbroken over a broken engagement. It's almost as bad as a failed marriage. Five years is a long time, though. It's time to put that away with the tutus.
What are you doing to change your situation?