1) You aren't free until outside the customs area. Don't do or say anything stupid when it can be held against you.

2) It seems like you hold a grudge for an incident that occurred to you more than 10 years ago. While not belittling whatever you went through (I've had more than my share of unpleasant immigration & customs experiences), it isn't healthy to let those feelings fester. I'd try to learn whatever lessons there are and move on rather than agonising on what you coulda or shoulda done in the past. Based on what you've shared there doesn't seem to be any follow up action you could take now. To keep dwelling on it only heightens the negative feelings you have and amplifies the impact on you. It does nothing to address what has already happened, or what might happen in the future.