Who should i trust, him or her? Please some advice?

Ok so i have been with my bf for about 5 months. He gave me a promise ring a couple months ago. I had heard that he had cheated on me and i asked him and her about it n they both denied it. Yesterday the girl confessed to me that it had all happened. I asked him about it and he denied it. His promises he ever breaks n he promised that he didn't do it. He said that he would go with me to talk to her mom, who apparently according to her, knows about it. I don't know who to trust, him or her But i don't know why she would tell me and she wants me to talk to her mom. Who do you think is lying?Who should i trust, him or her? Please some advice?
Probably your boyfriend. Unless she has a reason to tell you ...like she doesnt like you or something. My question is why would the Mom know what is going on? Talk to the Mom and see what she has to say maybe she does know something. Truly you will probably never know what really happened. You kind of have to kick him to the curb if you find out he was really cheating or except it and move on. I know from experience that is really hard to do. I guess it depends on how much you love them. The old saying of ';Once a cheat always a cheat'; may ring true with this situation. Good Luck.Who should i trust, him or her? Please some advice?
I would look into it more. He might have given you the gift because of guilt on his part for cheating. I would go talk to the girls mom if she says that her mom knows something about it. Make sure you know the facts before you believe either one of them over the other.
No one can answer this for you because we don't know them personally.