Should I tell the girl I love her if I've met her after years of not getting in touch?

honestly, you can't just broke up with a girl without any reason, especially if she loves you, and then come back and tell her that you're sorry, and you expect from her to forgive you, If I were you, I would keep my mouth shut, and let her live her life, especially if she forgot about you, if you come back to her life again, you would take away her happiness, and if you really love her, her happiness should come first before yours. But if she still loves you, you might have a chance, it will take a little time, but I think it will work eventually. Next time don't ask a girl out if you don't attempt to keep her with you.

I think you should first find out how she feels of you and if she feels the same way don't wait to tell her

WAIT!!! WHAT???
OK, slow down, don't tell anything yet. Yea... that might be her reaction right there.
Now here's my tip to getting her love you again and make sure this time you found true love. If you did not find true love then don't do it.
1. Start being friend first.
2. Apologize to her what happened previously.
3. When a year or two comes by and you know that you found true love then ask her for her contacts.
4. Start dating with her; after you got her phone number, and when you have realize that you are started to talk about your life and hers, also make sure the topic is getting deeper.
5. If all of the fail and you don't find true love then be her bestfriend. This will help you to settle your love that's still burning inside you.

In my own opinion, what you felt wasn't really love. You mentioned earlier that you didn't know if you really did love her but when you saw her ,after a long period of time, you realized your love for her. What happened to you was that when you saw her, you remembered all the things you liked about her before you broke up.But when you realized you lost what you had, your mind started convincing you that you still love her. One question is that was she occupying your thoughts after you broke up or was it a memory that faded away but cleared up when you saw her?If you didn't really miss her and be saddened by the fact that you are no longer together, then what you felt towards her that day wasn't what you thought it is. Something similar happened to me once, i liked a boy and he liked me but then i started doubting if i really do love him or is it just plain interest in him. He traveled and after a couple of months , we reunited. When i saw him, my heart beat so fast and i become nervous around him. I acted the same way anyone who is in love would act.I later realized that i felt these feelings in me merely because i know we had history together and i still cherish our memories together. What made me feel anxious wasn't my feelings towards him rather it was my memories acting up and reminding me of the good times and making me wish they came back. This wishing feeling causes you to think that you are in love when it is rather being attracted to her and not really in love. If you really did love her in the first place, you wouldn't have broken up with her whatsover.I'm not saying you can't meet her again and be friends. I am explaining the reasons of these mixed emotions.REMEMBER do this the slow way. DONT rush things and tell her you still love her because she wouldn't believe you. i mean come-on you broke up with her. I wish you best of luck with her and i hope you find the right one. Update us about what happens. :)