Sorry to hear that. Since you are failed refugee claimant, you will not be offered PRRA which would buy you 12 months before deportation. When you go there, please go with all children and bring confirmation of receipt for your HC. Please remain calm and cooperative, but bring all your HC evidences and tell them that you have a very strong HC case and you are kindly requesting that they give you administrative deferral of deportation so that you can wait for Stage 1 HC in Canada. If you fall on nice officer, they will defer your removal as they did for my partner and when you get AIP you will no longer be under removal.