My [18/m] girlfriend [18/f] of a year and a half wants to leave because she thinks I deserve better.

She was in an abusive relationship before me for about a year, and she believes she picked up some bad habits from it. She has a major problem with jealousy, to the point of if a girl says hi she gets upset. But that's the only downside to her, other than that she's a perfect girl. She's crazy about me, spoils me, brags about me, but she's just so insecure. She doesn't think she can change, so she wants me to find somebody who treats me better. What am I supposed to do? I've never loved anyone this much. I've built such strong relationships with her parents and family, I practically feel like she's already a part of my soul, but yet she wants me to move on. Please help.