From what I can gather Mexico has not yet legalized assisted dying but I think it varies state to state.

I have read stories on this message board about how difficult it is when someone dies here.

Closest place to you is New Mexico, but you have to deal with crossing the border.

States with Legal Medical Aid in Dying (MAID)

https://euthanasia.procon.org/states-with-legal-physician-assisted-suicide/

searched using - assisted dying mexico - sorted by last year.

https://html.duckduckgo.com/html?q=assisted%20dying%20in%20mexico