How can I get back his trust?

well all this happen after I gave birth. I get mad for a stupid lil thing. to get my anger away I have to hit my man. I brake up with him for stupidity but knowiin he going 2 beg me not 2 brake up with him. well I guess everybody well get tired of dis right? well he just had a cellphone and one day I check his cellphone and it was a lot of number which was not stored in his contacts I ask him whos dis numbeers and he said it was his boy and his mom cell well I told him to call because I really want to know he didnt want to and he got mad that he threw da phone and broke it and said ‘’u see happy you just dont want me 2 have a cellphone’’ but luckly I save da number in ma cellphone and I call myself when I call he was right it was all his boys and his mom celly well I felted bad because he broke he cellphone just to make me happy.well one day I was so bored so I check his voicemail and it was a girl sayiin that she wanted to talk to him because she heard that he has a son and his age is not really 15 so she dont think dis going 2 work out. well I call his house phone I was mad screamiin at him and askiin him who da hell is she but he denyed and at last I was like you know what stay with her and its over well that same moment he came to my house and he beg me to not brake up with him and that he aint do nuthiin wrong. well I calm down and I beg him to tell me da thruth and he said ok ima tell you da whole thruth so he was telling me that da other day he was chillin with his boy and he told her about our problems and that suppostly I treat him like a dog so his boy said ‘’oohh 4get her let me introduce you to sum chick but dont tell her your real age that your 19 say that you are 15 ‘’ so he did he said he was talkin 2 her 4 like 5 mins and then he left he was thinkin of breakin up with me and try to go out with da other girl and he call his boy and his boy said ‘’ ohh dont worried I already gave her your number’’ so he was like ok but then after he hang up he realize that he loves me and our son and dont want to mess it up so he aint talk to her nomore and he try to avoid her call and thats when she send them voicemail. well I gave him a chance but everyday I think about dis and after dis I change a lot im not agressive nomore I dont hit him infact we havent argue since that day but everyday I ask him if he still see da girl infact yesterday I talked 2 him seriously and told him that I cant b like dis my wholife so it will b better to brake up but he said no I swear I dont talk 2 her nomore and he promise me that he was going 2 show me that girl or she can tell me that between her and him didnt happen nuthiin only talkiin but I don’t know what should I do should I still b with him or should I brake up? how can I build up his trust???