FINISH HIM OR KEEP GOING OUT WITH HIM, I NEED HELP!!?

I'm 14, I've been going out with a boy for 2 years. He's amazing when it's just me & him, I've lost my virginity to him, young i know. But he's changed now, he's rude to les, saying to them ''tell your mam to stop wearing different lipstick, my d*ck's multicoloured'' - when I was there. & we were in English and he said something about shagging a l so hard lastnight that she can't walk, but everyone knows he's my boy. & were both popular, his bestfriend asked me out & even said that my boyfriend didn't deserve me cos' I'm too good for him, but I love my boyfriend alot, but hes not treating me right & he's rude & immature when he's with his mates, I'm respected by practically everyone but he's just ruining everything, I need help on this, he flirts with girls: what do I do, talk to him or finish him?z