When I first started looking at adding caliper studs on my 14 CS, it took me a while to figure out how to release the ABS sensor connector and I actually removed the sensor from the wheel carrier at one point. Attached are a few pictures that might be helpful. I think there is a tab inside the sensor so hopefully that's what you broke as I think it would be a lot easier to replace the sensor than the wire. Good Luck.
Yes, these connectors are tricky to get apart without breaking. If anyone has a clear explanation as to how to get them apart safely, I would be interested in it.