How can i forgive a unfaithfull fiance whom I have 2 kids with.?

I have a boyfriend who I was goin to marry soon , we have been together for almost 6 years I have always been faithfull , but recently I found out he was cheeting on me , I don't have proof but people are saying and my bf, has changed a lot . i left him for a few days but he told me thet everything is going to be different so I decided to give him another chance, but since then i dont trust him i sometimes hate him , and sometimes I need him , I am so confused , I am deppresed, we had a great big fight so we are separated now , he says he misses me and that he wants to get back and that he accepts that he has been wrong and that he will be a better husband and he wants to get married soonand he doest want to lose his family . I am really confused.