angry at friend

disclaimer: this is a little drama heavy lol

so one of my friends, lets call her serena on here, has been hanging out with this other girl "jolene". is it bad that i feel so, SO angry seeing them together? 

all jolene does is hate and hate on people, but barely anybody hates her back. im p sure she only got together with serena because she's not emotionally strong enough to get away from her. almost like she's scared of her.

serena has complained abt her b4 to me, but whenever they're together she acts all cutesy and friendly. and then she says like "oh im fine w/ her now its ok"

idk if this is just jealousy or what cuz like she just fucking suck