GIRLfriend and i fight alot and i love her but she hurts and doesnt trust me anymore?

We've been dating for more than a year and a half, my girl checks my phone, gets mad i talk to and hug girls, she gets jealous of her own best friend cause we talk alot and i go to her for advice, and i cheated once more than a year ago by kissng a girl back but i pushed afterwards and she knows i love her but she doesnt trust me..... How do i mae her trust me and us fight less? And i sometmes hide stuff t avoid fighs.....