Should i tell her im jealous?

lately ive been pretty mellow alot of things have gotten to me but ive tried to be cool about it . but sadly by bff noticed i was all mellow , i lied to her and just told her it was a blah day. but the truth was is one of the reasons i was all blah was becuase i was jealous of her. she gets whatever she wants and well it buggs me that i cant have that or that she gets it and i was thinking i was going ot tell he ri was jealous of her but nicely and not send they message ur jealous. i odnt wnat to hurt her i just nwat her to understnad and so she doesnt feel im hiding stuff from her.? is it a bad idea?