My boyfriend cheated on me what will i do?

Me and my boyfriend are going out 2 and a half years, he is 20 and i'm 19 we have a baby together he is 1 it is always rough between us meening were always fighting or shall i say i'm always in a bad mood with him i don't know why but i kinda pushed him away, now i recently found out he cheated on me with 1 girl they were texing and they met up once and kissed, i can't stop thinking about it and i don't know what to do were practically back together but i do want to be with him but o don't in a way?HELP?????