Neither I nor Xi made that claim.
China told the British to stop selling opium because it was damaging China's economy (by extracting silver, which Chinese taxes were denominated in), making more Chinese turn to drugs, creating a virtuous cycle for British East India Company and other drug traders. The British refused because they wanted Chinese tea but were unwilling to pay in silver, which was the only payment China would accept because China didn't want British goods, so the British used military power to establish British-owned ports to import opium for silver (using some of it to buy all the tea the British could drink) and dictate Chinese trade policy.
Without the opium trade, none of this would have happened. China likewise doesn't care what the US thinks about fentanyl damaging the US economy, with the total damage estimated at 7% of GDP in 2020. https://www.jec.senate.gov/public/index.cfm/democrats/issue-...
It was a war about power and sovereignty. Losing those is bad. It's only related to opium because the inciting incident was British worry over an opium law.