A few points, DA.
1. Only 300W for 4 minutes? I think it's time for a new power dial, yours seems to be dying. OMG 300W!1!!1111 just doesn't have the same ring to it.
2. If you were only going 26mph in that break and the peloton was averaging 26.5ish for the race, there wasn't any way you were staying away, with help or without help from the guys that bridged.
3. When people bridge to a break, it requires a pretty hefty effort. Cut em some slack and let em suck some wheel for a minute or two while they recover instead of expecting them to pull right away. You weren't off the front for that long, so by the time you guys were caught they probably had just recovered.
4. They coulda just been covering for teammates in the peloton or trying to pull the peloton back to you