If there is only one person for everyone out there, I suspect that most of us end up with someone who's not are soulmate. And you know what, I bet most people's relationships are just fine with out being soulmates.
Your friends who ended up being cruel to eachother, maybe they were soulmates in the sense that they deserved eachother, but I don't really know them so I'll withold judgement. But seeing that spell fail before might have shaken your confidence in the spell, making it weaker or even sinister. I recommend you assume it was a complete failure and and nitpick anything that went wrong. Magic doesn't stand up too well in the face of derision. You make wish to take a bath with some salt in it, and cleanse your chakra to get rid of any vestiges of the spell.
Make your own spell based on the old one, with your own personal improvements, it'll work better if it's personalized.
You may wish to use a spell that attracts a romantic partner you can be happy with for a long time. A spell to see your soul mate has a very big problem, there's no guarantee of meeting them. It's also really restrictive and specific and might limit your options for happyness.
I hope this helps. Feel free to send me a message if you want specific ideas for a spell.