Ma bff defends my bully (vent)

So to enter yall in context , my 4 grade bully and ma bf are friends since like a year. I dont really have a problem w/ like idgaf but when I tell her what he did 2 me in a vent way , she starts defending him like "I never saw that" "He said me that you lie" (Bro tells my vent to other ppl) and with an excuse like "I wanna know both sides!!!1" "Yes I believe ya BUT-" . I feel like I wanna end that friendship, she isnt bad tho...