I had almost the same situation, although it was at a crossing with a crosswalk light and I had the light. A goof in an SUV wasn't looking and kept coming even though his light was red. He looked over, saw me crossing and slammed on the brakes and came to a screeching halt with his front tires in the crossway. I was almost up to him and a pickup truck came from behind slammed into his rear end pushing him well past the crossway. I gingerly made my way through the mess and kept going. I could hear him screaming at me but just ignored it.
There was no way I was going to become a party in that mess. It was clearly Mr. SUVs fault for nearly running the light and the pickup truck was at fault to for following too close. I was worried I would somehow get sued or a dumb arse cop might try to pin some liability on me - so I just kept on going. All I did was press the crossway button, wait for the white light and went when I had the right of way. I just didn't want someone with deeper pockets or connections linking me to this accident. They caused it, they could take care of it. Yeah, I am a bit calloused, but I worked long and hard to get where I am and wasn't about to have to lose a good chunk of it and have to hire a lawyer for something that was not my fault.
OP, you were right. No guilt should be wasted on this. The lady had what I call "unwarranted altruism" and decided to stop even though you were waving them on. Had you crossed anyway the dump truck might of slammed into her and her into YOU and we might not be reading your post.