Learn English – What does ‘got popped’ mean exactly in this context

The nearest meaning is crash after a drug high [link]

Hangover or other ill physical and psychological after effects as a result of a drug leaving your system and your body craving more. Specifically , this term refers to amphetamines, though it's often used to refer to other drugs as well.

The crash from the speed was so bad I couldn't move from the corner I was crying in for 3 hours, until I found my fifth of jim beam.

In the linked post, the original poster says:

From going from an emotional wreck with bugger all sleep to a happy single man with a huge life ahead of him in 3 days is surreal. How did I do it you may ask? I fucking sucked it up thats how. I focused on the facts not the emotional pain I had experienced all of 18 hours before. I put a call out on facebook to family and friends (my profile is private and only have true friends and family members) and I had a whole village come to my call!

This is essentially euphoric - like euphoric high similar to that from a drug. The answer says this will end soon, and end badly, with a very bad depressive feeling - "a crash", and the asker will need help of friends in making the actual recovery.

If a thing is slap-bang on, it would mean "exactly right". His answer to the quiz was slap-bang on.

That said, one would not usually refer to a person as being: slap-bang on.

Please note: the term is slap-bang [right, as in right in the middle of] and usually referring to a THING, not a PERSON. Slap-bang is used to intensify: the dog was slap-bang in the middle of the road.

The other term: to be bang on means to be right. slap-bang on merely makes it stronger.

So, if you want to join /bang on/ the verb to /slap-bang/ the adjective, the best way would be: slap-bang on.

That said, it is very odd to say that: Princess Diana was slap bang-on. The only meaning here would be: She was right about the royal unspoken code of marriage.

That means: She knew that if Charles could have Camilla, then she Diana was perfectly justified (slap-bang on or right about) about having that lover of hers (I forget this name).