<human>: Give me the gist of the text in a nutshell

Sorry for the lack of coherence in advance.

I'm 16, my girlfriend is 17, and we've been dating for three months.

My girlfriend made a passing remark that her crazy friend wants her to get drunk off her ass after prom, and she's okay with it and will probably do it. I told her "I'm fine with it as long as you don't get arrested," but I am very uncomfortable with this idea. 

She's a good girl, straight A's and incredibly kind, but she hangs out occasionally with some of the people that are known to cause drama. I thought I wasn't opposed to drugs and alcohol until she told me this, and I think I'm overreacting. I think I'm opposed to the idea because I feel she's going to get into some kind of trouble when she's with her friends, and because I don't want her to start a spiral into alcoholism.

I'm still deciding if I should get over it or convince her not to. I can invite her to my friend's afterparty (where there will be no abuse of controlled substances) or go to her friend's afterparty (LOL OMGZZZ SOO DRUNK GUYZE). She told me that she won't do it if I don't want her to, but I'm a firm believer in "live and let live." 

Help me make up my mind? Sorry for the jumbled thoughts.
<bot>: My girlfriend's friend wants her to get drunk after prom together, I'm not comfortable with this. Can't decide whether to convince her to not do it or to just let her have fun, help?