Will my ex-girlfriend choose me?

I know it's long but pretty please read this, it's important and I really need help.

Me and my girl met three years ago and we asked each other out in January of this year. We soon became boyfriend and girlfriend but she later mentioned that she already had a boyfriend that's from another school (she told me twice). On Saturday night she told me this the second time and I felt so upset and she was mad at me for some reason. This made me felt so upset that I almost committed suicide the next morning but I didn't do anything about it. She loves me and always tell me that everyday and every time we see each other, we hug each other. She had all feelings for me after three years although she had a boyfriend. She also call me "sweetie pie" and sometimes "sweetie pie with a cherry on top (sometimes with whip cream)". Her boyfriend was her first love but she been in love with me since we first met. I ask her this: "If you never had a relationship with that boy, would you have one with me?" She said, "Yes, I would love to have a relationship with you." I just couldn't believe I went through all of that for six weeks and I thought everything was a lie, I even started to not like Valentine's Day because me and my "girlfriend" gave each other presents for that day, like I wanted to forget about it. I also started to think that women like her are liars and cheaters but I stopped believing that for some reason. I also wanted that boy dead or myself dead in the future. Yesterday I ask her if she can be my ex-girlfriend because 1) we ask each other to be boyfriend and girlfriend and 2) we "broke up" over the weekend but we still love each other no matter what. She accepted so now I'm happy but nothing makes me more happy than finding someone that I have feelings for who also have feelings for me. I don't know what to do. Will my ex-girlfriend ever choose me over that boy or is she sticking with him because she met him first? Should I wait a little more since we are an ex-couple (if that's what you guys can call it)? I'm really worried about what might happen between me and my ex... she might get hurt or something and I'm really nice as her... and playful like her. Please help! What should I do?

- I already talked to my parent/guardian.

- I already gave my ex-girlfriend some time in January but still choose that guy up to Saturday night of last weekend.

The root to Saturday night's problem was the fact that I told her that I wanted our relationship to late as long as we want and I know she wanted to do the same, that's when she said we are not really having a relationship all that time.