回复：回复：回复：谁能帮我 -- 不应该发生的事

That was a strange thing. According to my understanding, at least you tried to pass the border legally. If the CBP officer found out that you did not have enough document to enter Canada, you would be directed to return to Canada immediately. One of my friends wanted to visit Peach Arch Park but accidentally drove directly to US Customs. He was asked to return to Canada by US CBP officers. With his BC driver's license and his BC car registration, he entered Canada without any problem.
Anyway, CBP officers are not well trained sometimes. This Wednesday, I showed CBP offciers my Re-entry Permit at Peach Arch US Customs. Three out of four offciers did not know the function of the Re-entry Permit.
I agree that you should talk to an experienced lawyer before you leave US. Once you leave, things may become more difficult than if you stay.

Good luck.