How to get my gf back?

Hi I'm 17 and iv been dating a girl for 2 years (she's 18) and we have had our issues in a relationship and iv always wanted to fix them, no listen I haven't been the best of bfs, I lied to her alot, I was very perverted towards her and it would often hurt her, I played head games with her perposely so she would stay with me, iv called her many names before when I got mad at her, and I have even hit her before (but nvr in the face) buts she's also done alot if the sane (except lie, I have a personal problem with that) we argue alot and she's always calling me immature and to grow up, even thougjvi think I have ADD but my mom won't pay for the testing, idk wat to do anymore we have been on the edge these past two months we broke up twice and she liked two different guys but they rejected her and now we are on the verge to getting back togther again, now that I think about it I don't deserve her and she deserves to be happy...if we do get back togther I need to kno how to be a better bf and how to take care of her better, I do care about her ALOT and I will always love her but I just want her to be happy, if anyone can give me any kind of advice about being a better bf or better person or wat to do in this situation...please help..,