Confused, Found myself in something that i feel so trapped in, Need some Advice

I was with this girl for about 4 months before she wanted a break from being together because she wanted to date other guys.
We are both in our teens.
But the problem is that we havent completely broken and she has been wanting me around while she dated other guys.
I dont know if this would be my own fault for not saying we should break it off for good.
But I guess my mind just wants her back, but Ive been through so much heart break and had to deal with so much stress it almost killed me (I got an infection that was close to poisoning my blood caused by stress)
I dont know what to do now since its been more than a year since we met each other, i feel like im just a rebound and she gets pissed at me if I mention this. She has cried over guys since dating and I ran into some stuff she hoped would happen with the latest guy which teared my heart so much I lost my mine.

My love for her is slowly dying and I dont trust her but I dont want to break anyones heart. Like if I when in dated someone I dont want to break my ex's heart and I dont want to break the one im dates heart if she wants to get back.

Im confused, lost and through all the shit Im just stuck but very strong after it all.
The reason why i dont leave is because shes my first girlfriend first kiss first time and I still have feelings for her and sometimes feel like i can trust her

Let it go. Say goodbye to her, she's no good for you. I know how hard it is to say goodbye to your first love, but honestly, you've just been with her four months, that's not that much. And continuing with her can only lead to more pain.