How to get my ex boyfriend back?

ok well my ex boyfriend just broke up wit me bout a week ago and probably a week before he broke up wit me he had another girlfriend then he lied 2 me when he was braking up wit me and he said he needed 2 b single 4 a while and I told him what ever I don’t care and then my frnd emma told me he had another girl that he had a new girlfriend and so I askd him bout it and he lied 2 me and said no he didnt and I told him that someone that I trusted and that wouldnt lie 2 me had told me he did and then he finally told me the truth that yes he did have a new girlfriend and I no that he has lied 2 me a bunch of times like prtty much our whole relationship was lies he told me he wntd 2 marry me and he wntd me 2 have his kids and everythng he is still wit this girl and I really have no idea at all but I still love him so much and I want him back so bad but I don’t no why tho because he treatd me like crap most of the time when we were going out and lied 2 me all the time everyday he lied 2 me bout sumthng but I still want him back tho and I have no idea why and I was just wonderin if anybdy could tell me why I want him back and mayb how 2 get him back srry its kinda long but please help if you can thnx muchz =]