Toxic or Kind, problem is i love my toxic ex and im not sure about my new girlfriend, M15, Ex: F16, New: F15

Who is the the right girl despite the aspect of the relationships?

I just turned 15 and i have been with an amazing girl for about 2 months, she has never done a single thing wrong and i mean that with my whole heart, no mistakes, makes me feel good about myself, kind and understanding. However, my ex girlfriend just because single and spoke to me when she saw me out with a few of my friends, her tone was extremely flirty and said multiple times that she ‘missed me’ and ‘wants me bad’ the whole time we had a conversation. Our previous relationship was a year and a half long, and she was really struggling with insecurity, resulting in toxic feelings and forcing me to block certain people she found ‘not comfortable’.

I mean it when i say i cannot resist my ex, like despite us breaking up 8 months ago i can’t help but feel like i love her despite the toxic problems and my perfect relationship now.

My friends say follow your heart to me, which is 100% my ex, but my family and in my head i know my new girlfriend is almost perfect.

Go in depth please and tell me whether i should follow the girl who i genuinely do love, or stick with my new girlfriend.