I need help. asap.. boy problems!!!!?

okay so im a freshman in high school. im dating this sophmore and he broke up with his ex for me and she seen us kiss so ever since she has been texting him and trying to get him back. she called me and blame me. she said he cheated on me with her so i asked him he denyied it so i had her to come up there and he just wal;ked off. so i found out he cheated on me i said i was done with him and he cried in 4th block and was begging for me back but that night he came to her house and they had she told me about it. and he was like "baby no we didnt, i dont want her, im serous this time no games, i only want you, your my everything ,im done with her, she is a , will you please give me one last chance" so i took him back and his ex is all up my back about it. do you think he will cheat on me again? i told him if he does im done for goodno more chances. and he has never ever cried over a girl til i told him i was done. friday he couldnt even look at me because i was soo heart broken i cried all day he would look at me and say " im sorry taylor, i love you" i just said eff u and walked away. but i think he cares.. what do u think?