I'm playing Fallout 2 for the first time, and didn't realize how devastating and hard-to-get-rid-of Jet addiction is. Is there any cheat I can use to just get rid of it?

I haven't played FO2 for a long time so I'm a bit rusty,

Dunno about cheats but in FO2, there's a sub quest to find a cure for jet but I'm not sure if you can use the antidote on yourself as it's meant to be a quest object. Anything more than this is probably entering game spoiler territory,

Failing that, you can go to the stables and kick living the shit out of Myron for making jet :D

There is the quest mentioned above, but you could

[spoiler]
travel directly to San Francisco, one of the merchants in the tanker stocks Jet Antidotes if I recall correctly.
[/spoiler]

I can confirm Yarilo's solution.

Heroin's a b*, eh?

What Yarilo said or you can do the quest line to to develop the antidote. (You need to be able to travel to New Reno)